.

No tools.  Just push the detent with a pen or bullet tip and keep turning it counter clockwise until it comes out.  The detent and spring will pop out.  Just put it all in the other sight just as it came out and twist it down untill the top of the base is about even with the flip up sight then re -zero.

Now if you were talking about the front sight BASE, then I have given you the wrong direction.

Here's alink to a website where you can buy the individual parts.
They are each labeled on the diagram individually, so you should be able to see the pins that you need to remove.  You have to remove the 2 roll pins that attach it to the barrel, and the one that attaches the gas tube into the front sight base.

www.adcofirearms.com/barrel_parts.cfm?page=woa