rvm --help clearly shows how to remove it:
implode :: (seppuku) removes the rvm installation completely. This means everything in $rvm_path (~/.rvm || /usr/local/rvm). This does not touch your profiles. However, this means that you must manually clean up your profiles and remove the lines which source RVM.
That is, the RVM itself is sawed off with one command:
rvm implode
This will erase all the interpreters installed in its framework, gems and source codes of extensions. Plus, you will need a small sweep of the shell configuration files ( .bashrc , .bash_profile , .zshrc , etc.) manually from the lines in which RVM is mentioned.
If you still managed to install ruby , rubygems or something else related to Ruby from the system repositories ... Leave. RVM will allow you to switch to system Ruby if necessary, it will not hurt you.
But if it still interferes, erase it through Synaptic, it is in the system by default. Most likely enough "complete removal" (purge) packages ruby and rubygems . When deleting, you will have to erase all dependent packages, and the removal process will ask for confirmation. Scroll through the list to see if anything is there.
That's it, go to the RVM website and follow the RVM installation instructions from there.