$ sudo apt-get remove fonts-lyx 

Uninstall fonts-lyx including dependent package

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

$ sudo apt-get remove --auto-remove fonts-lyx 

Use Purging fonts-lyx

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

$ sudo apt-get purge fonts-lyx 

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 fonts-lyx 

See Also,