$ sudo apt-get remove libxenomai1 

Uninstall libxenomai1 including dependent package

If you would like to remove libxenomai1 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove libxenomai1 

Use Purging libxenomai1

If you use with purge options to libxenomai1 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge libxenomai1 

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 libxenomai1 

See Also,