$ sudo apt-get remove emacs25 

Uninstall emacs25 including dependent package

If you would like to remove emacs25 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove emacs25 

Use Purging emacs25

If you use with purge options to emacs25 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge emacs25 

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 emacs25 

See Also,