I want use CCleaner on Ubuntu 10.04. But I do not know whether it is necessary or not.
Is it necessary? Are there any benefits from using it?
CCleaner is a windows application, even if you run it with Wine, it won't make any sense to do so because it removes files based on their file paths which is totally different on Ubuntu. Other programs ran by CCleaner have similar issues and registry cleaning will only affect the wine settings of CCleaner.
So, in no way is CCleaner beneficial on Ubuntu.
Bleachbit is the equivalent. Watch your settings (especially with browser settings). Also run:
sudo apt-get clean
This command removes previously downloaded archives which can safely be removed. Those archives are only used for faster reinstallations of programs.
You can also save a tonne of space by removing old unused kernels. You can save further space by uninstalling LibreOffice / OpenOffice.org and installing Abiword if you only use writer, install gnumeric if you also require spreadsheets.