Hi, this is probably a really stupid question but I can't seem to figure it out 
Ok so I have the city mini single and I am thinking of buying adaptors so the maxi cosi can just clip in.
I know where the adaptors go, but there is little plugs in the hole. How do I get these plugs/hole covers out?
I can't seem to find anything online. All the youtube videos show the holes just open, no covers/plugs.
Please help! Thank you