tcz can be removed with no problems. this is because tcz is barely ever installed. (it installs almost nothing.) tce can be removed also. you would think it's a bad idea, but the mechanism that performs the uninstall is really exceptional. both have tools called tce-uninstall and tcz-uninstall, and sometimes you need them to remove a package. you just open the term, type "tce-uninstall" (or tcz for tcz) and the rest should be easy.
for ppr/tce and ppr/tcz removing a package is easier: delete the actual tce or tcz file from the tce folder and reboot. depending where its kept that may not remove everything (like flashplayer) that was not really part of a package, but downloaded by a download script (flashplayer is not technically part of any package.) you could try to treat that as a bug in tce-uninstall and see if flashplayer can be added, even though i believe tce-uninstall downloads .dep files or .list files, and neither file will list flashplayer itself.