A package can be uninstalled via the Puppy Package Manager, (this doubles up as a way to see what is installed):

• In Lucid Puppy 5.2x - A list of installed packages is shown in the main window, un-install packages by selecting one from this list.
• In Slacko Puppy 5.3x - Click on the 'uninstall' button. A list of installed packages is shown, un-install packages by selecting one from this list.

Slacko screenshot

Some PETs may not uninstall cleanly. If unsure make a backup of your Pup Save File before and after installing packages (frugal).

An alternative is to use UnPet, which is quicker than waiting for the PPM to load up.

SFS packages are unloaded via the BootManager or SFSLoad. As SFS files are read-only and less likely to uninstall uncleanly.

To remove package that are built-in to the BaseSFS use:
PuppyMenu > Setup > remove builtin packages

Puppy Package Management
PETs - software packages
SFS - sfs format packages
UnPet - quick removal of Pet packages
uninstalling
Software Index

Guide Installing and Making Pets page
Guide to making PET files on forum
PET does not contain all the files in the folder - thread
How to un/install a Pet file from the command line thread