What size tool do I need to remove trigger and hammer pins from receiver with CMC drop in?

I traded for an ar rifle with cmc drop in trigger and i want to remove it but did not get allen wrenches. I do not know what model but told it has a 2 1/2 pound single stage pull.
Update: They are round top screws that go in the ends of the pins. Sorry i did not make that clear.
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