Can I deactivate Anti Theft online? *URGENT!*

due to a provider change I changed the sim card and forgot to deactivate anti theft.
It started the alarm when I booted the cell phone.
When I inserted the original sim and tried to boot (to deactivate anti theft) the alarm fired again.
The friend phone number may no longer be active.

Is there any chance to get the mobile running again?

login at https://my.avast.com and set the phone status to “found” to start with.

when put on ‘found’ how long does it take to be able to enter my phone? i am waiting for over an hour to do so …