IMEI change

The IMEI of a phone is like the VIN (Vehicle Identification Number) of a car. It is built into the hardware, and it can't be changed any more than the VIN of a car can be changed.

The IMEI has nothing to do with security, and it can't be changed anyway.

It doesn't make any difference even if they can. Your phone number is what they're interesting if the police are trying to track your calls and cell locations. If this person had put in a different SIM and done something illegal involving your phone (which you have no proof of, just paranoia), then nothing traces back to you anyway.

Only the hosts who maintain the forums can remove a topic. And they'll usually only do so for specific reasons.

Since there are a lot of questions and responses here that would already answer other folks questions looking for the same information, they would be unlikely to remove it.

The IMEI and SIM also have nothing to do with each other. The SIM determines what carrier your phone can communicate with. That's it.

All the IMEI does in relation to that, normally, is for you to let your provider know that number. That tells them what model phone you're using. The purpose for that is so they can set up that pairing on their end for the best possible communication with their satellite and cell service.

Still, other folks should not know that number. We see them posted here often, and ask the hosts to remove them as quickly as possible. With that number, a person could claim the phone is stolen and ask to have that IMEI blacklisted so the phone stops working by denying access to the provider's service. Any good provider should refuse to do this without proof the phone actually belongs to the person asking for it to be blocked.