Accidently installed two versions of swi-prolog, need help to fix it

Accidently installed two versions of swi-prolog, need help to fix it

Alright, I have this problem where I installed two different versions of
swi-prolog.
I manually installed swi-prolog (swipl) version 5.10.4 from a tar-file,
which I see now is a stupid thing. (I can't remember why I did this
exactly, but that is besides the point.)
Then I wanted to get the newest version of prolog, so I followed these steps:
sudo apt-add-repository ppa:swi-prolog/stable
sudo apt-get update
sudo apt-get install swi-prolog
Now if I do
swipl --version
I get
SWI-Prolog version 5.10.4 for x86_64-linux
And if I do
/usr/bin/swipl --version
I get
SWI-Prolog version 6.4.1 for amd64
I only want the 6.4.1 version on my computer.
I searched the internet for hours, but I couldn't find out how to solve
the problem. (Maybe I've been searching for the wrong terms/tags, I don't
know..)