The removal of the ~/.lazarus removes the complete lazarus config.
The trouble is that most package systems leave the configuration behind on deinstall, so for a full refresh do:
1. remove the lazarus pacakge in software center
2. remove the ~/.lazarus dir
3. install the lazarus package again. This will probably make some Ubuntu default ~/.lazarus
The lazy would simply manually configure lazarus though. There are only 2 or 3 settings to do.