how to remove battery from a class 2 level 4

My dad bought an aventon bike for us to use and we are trying to figure out how to charge the battery, we've got the cable and whatnot but we can't really fit it in the house, but the garage we have is ancient and doesn't have any outlets, meaning charging the battery is going to be tricky if I cant remove it. every tutorial I've seen says to use a key with the bike, however our bike didn't come with a key, nor does it need one, I was able to take it on a test run without issue. can I even remove the battery from the bike? if so how?