uninstall adobereader-en 9.5.5 on Ubuntu 18.04

Assuming this package was installed with apt earlier. This does not work for Wine apps etc.

use

Apt list - Adobe installed *

to search for installed packages. If you find what you want to uninstall, then

sudo apt purge package name

where package_name is obviously the name of the package you want to delete, found with the previous command.