Hello,
I'm new to mikrotik and here is my situation:
I have a wireless modem router that is connected to port 1 of my RB750 and port 2 of my RB750 is connected to my PC's NIC.
I setup a hotspot for my wired network and through User Manager I added a few accounts and everything works great. Now I want to restrict access to my wireless network through my RB750 and User Manager but I don't know how should I accomplish that.
Could you please help me with that? Thank you.

Any suggestion? I'm still stuck.

Reallllllllly?????????????????????????
I'm in MIKROTIK forum and I have a MIKROTIK related problem and there's nobody here to help me solve my MIKROTIK problem??????????
THAT'S AWESOME!!!!!

Your problem is not mikrotik related. It is related to your wireless access point that you didn't tell us anything. Just that it is not mikrotik obviously.

Now I want to restrict access to my wireless network

you can do that on your wireless device. other devices can't control access to your wireless device.
since your AP is not mikrotik, this question is not really relevant to the forum