$ sudo apt-get remove g15composer 

Uninstall g15composer including dependent package

If you would like to remove g15composer and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove g15composer 

Use Purging g15composer

If you use with purge options to g15composer package all the configuration and dependent packages will be removed.

$ sudo apt-get purge g15composer 

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 g15composer 

See Also,