$ sudo apt-get remove pidgin-otr 

Uninstall pidgin-otr including dependent package

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

$ sudo apt-get remove --auto-remove pidgin-otr 

Use Purging pidgin-otr

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

$ sudo apt-get purge pidgin-otr 

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 pidgin-otr 

See Also,