Can a police officer disarm you just for OC

I was recently stopped while open carrying in Hales Corners. As I was walking down the sidewalk I seen a cop waiting for me so I just proceeded on my way because I wasn't doing anything wrong. When I came up to the officer he Grabbed my arm and made me put my hands up while he started to disarm me. I responded that I do not consent to any search or seizures and asked if I was being detained (which he said no I wasn't). he then continued to pat me down after taking my fire-arm.

If I'm not being detained then I should be free to go but how can I do that if they have my fire-arm.

Is this legal for them to do?

Can a police officer disarm you just for OC