Unable to uninstall a package showing via apt list

Question

I am running Ubuntu 20.04LTS. When I search for virtualbox in my packages, it shows a number of packages.

~$ apt list | grep virtualbox

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

boinc-virtualbox/focal 7.16.6+dfsg-1 amd64
unity-scope-virtualbox/focal,focal 0.1+13.10.20130723-0ubuntu2 all
virtualbox-dkms/focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64
virtualbox-ext-pack/focal-updates,focal-updates 6.1.10-1~ubuntu1.20.04.1 all
virtualbox-guest-additions-iso/focal-updates,focal-updates 6.1.10-1~ubuntu1.20.04.1 all
virtualbox-guest-dkms-hwe/focal-updates,focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 all
virtualbox-guest-dkms/focal-updates,focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 all
virtualbox-guest-source-hwe/focal-updates,focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 all
virtualbox-guest-source/focal-updates,focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 all
virtualbox-guest-utils-hwe/focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64
virtualbox-guest-utils/focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64
virtualbox-guest-x11-hwe/focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64
virtualbox-guest-x11/focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64
virtualbox-qt/focal-updates,now 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64 [residual-config]
virtualbox-source/focal-updates 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64
virtualbox/focal-updates,now 6.1.10-dfsg-1~ubuntu1.20.04.1 amd64 [residual-config]

However, when I try to remove either of them, it says that that package is not installed, so not removed.

$ sudo apt-get remove virtualbox-dkms

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'virtualbox-dkms' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

--- 
~$ sudo apt-get remove virtualbox-source

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'virtualbox-source' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

---
~$ sudo apt-get remove virtualbox-guest*

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Note, selecting 'virtualbox-guest-utils' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-modules' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-additions-iso' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-dkms' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-dkms-hwe' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-modules-hwe' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-x11-hwe' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-source' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-source-hwe' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-utils-hwe' for glob 'virtualbox-guest*'
Note, selecting 'virtualbox-guest-x11' for glob 'virtualbox-guest*'
Package 'virtualbox-guest-modules-hwe' is not installed, so not removed
Package 'virtualbox-guest-additions-iso' is not installed, so not removed
Package 'virtualbox-guest-dkms' is not installed, so not removed
Package 'virtualbox-guest-dkms-hwe' is not installed, so not removed
Package 'virtualbox-guest-source' is not installed, so not removed
Package 'virtualbox-guest-source-hwe' is not installed, so not removed
Package 'virtualbox-guest-utils' is not installed, so not removed
Package 'virtualbox-guest-utils-hwe' is not installed, so not removed
Package 'virtualbox-guest-x11' is not installed, so not removed
Package 'virtualbox-guest-x11-hwe' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Could someone help me understand what's going on here? I am fairly new to Linux. Loving it but still get confused by such things. Thanks!

Update: I get different results when using dpkg and apt list as shown below:

~$ dpkg --list | grep -i virtualbox
rc  virtualbox                                 6.1.10-dfsg-1~ubuntu1.20.04.1         amd64        x86 virtualization solution - base binaries
rc  virtualbox-qt                              6.1.10-dfsg-1~ubuntu1.20.04.1         amd64        x86 virtualization solution - Qt based user interface

~$ apt list --installed | grep virtualbox
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Answer 1

apt list | grep virtualbox lists the available packages in your software sources that can be installed with apt. You need to run the following command to list the packages that are currently installed with apt:

apt list --installed | grep virtualbox

Please note that this command will return an error message if you try to run it with apt-get instead of apt.

This command will return a shorter list of packages because the results of sudo apt remove virtualbox-dkms virtualbox-source virtualbox-guest* show that many of the packages that are listed in the results are not currently installed.

The results of dpkg --list | grep -i virtualbox show that these two packages are manually installed: virtualbox and virtualbox-qt. You can uninstall these two packages with the following command:

sudo dpkg --purge virtualbox virtualbox-qt

The packages are selected to be purged (i.e. we want to remove everything from system directories, even configuration files). This would be a good command to run if you are planning to install a more recent version of VirtualBox.