ModdIt
Hi algori,
assuming you are new to Linux debian based, find the package name which is really easy in using the tool synaptic,
depending on your antiX version you might wish to install it. You can remove firefox from there.
This way you and others can help themselves, there are plenty of other ways for more advanced users, i propagate this
one as it is easy to understand and use, also gives some insight in to the wealth of packages available for antiX.