Hey there. I've fiddled around a little with free VPNs from the Firefox add ons (namely Urban Free VPN proxy Unblocker and ZenMate Free VPN). Now I've removed the extensions and I wonder if it's enough to entirely get rid of them? I want to avoid to get tracked by some VPN provider although I've removed them. Are they somehow sandboxed or something? Sorry if the question is redundant, I've tried to search for the correct terms and couldn't find an answer.

Thanks in advance, people!