That would be :
removepkg [option] packagename
The 4 options are:
-copy= copies to preserved package directory,creating a tree of original pkg without removing it.
-keep=used for debugging
-preserve=same as -copy but removes original pkg
-warn=shows what will happen if the pkg is removed
Most of this is cribbed from the Slackware essentials manual to help make this reply more understandable to someone besides myself
Note:you can only use one option at a time but you can list more than one pkg. I hope this helps.