Someone stole my phone at school, and either removed or deactivated the SIM card so the location is not able to be found on my Android Device Manager. Can I track it without the SIM card myself?
It depends on the phone platform, whether you have tracking set up in advance and whether someone is foolish enough to break into your account while on Wi-Fi or leave the phone on while in reach of a Wi-Fi you've previously connected to.
So the realistic answer is probably not though the sooner you try, the better.
Anyone with any brains would have factory reset the phone immediately after removing the SIM.
If you signed it into google tracking or have the IMEI you can track it. Also report it and soon as he puts another SIM he's screwed. You used to be able to ENC someone and listen to their calls. He could change the IMEI also. Doesn't matter if SIM is removed, phone has an IMSI, it can be tracked. Police won't bother finding it or tell you that.
I put a GPS Tracking sticker inside the phone where its hard to see and find it anywhere in the world. Hell I can even GPS disrupt a Drone thats flying past, lol.