$ sudo apt-get remove ruby-bcrypt 

Uninstall ruby-bcrypt including dependent package

If you would like to remove ruby-bcrypt and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove ruby-bcrypt 

Use Purging ruby-bcrypt

If you use with purge options to ruby-bcrypt package all the configuration and dependent packages will be removed.

$ sudo apt-get purge ruby-bcrypt 

If you use purge options along with auto remove, will be removed everything regarding the package, It's really useful when you want to reinstall again.

$ sudo apt-get purge --auto-remove ruby-bcrypt 

See Also,