texts coming in but I gave away the tablet

Hello.
I had a Samsung tablet some time ago, and I think I installed this software back then. The thing is I gave away the tablet to a friend, and the he gave it to someone else etc…
Now I keep getting these texts that someone changed the SIM card, I get it’s mobile number and tablet IMEI in some texts on my mobile phone, and on girlfriend’s phone (maybe I added her number as well?)
How can I make this stop? I have no way of tracing the tablet, nor do I want to. I just want these sms’s to stop!
Any help?

Hello,

as you have the phone number of the new owner, it would be best to contact him and ask him to re-configure/uninstall Anti-Theft.

if you still remember your avast! PIN, you can also disable Anti-Theft remotely:

SET PROTECTION
Sample: 2222 SET PROTECTION 0

Will enable or disable Anti-Theft protection (0 = turn off, 1 = turn on)
Caution: By using this command you will
completely disable the avast! Anti-Theft system
thus rendering the Anti-Theft protection useless.

Be aware, that your SMS command will be visible if a) the user upgraded to android 4.4 meanwhile b) the avast! PIN is incorrect

Regards,
Werner

Well, it’s a tablet so I can’t phone the user. I will try the sms thing but this is stupid, I don’t want sms from some device I’ve used…

Well, all I could do was send an sms to the number that I got the sms alert from. Nothing happened.
I really need this to stop right now, it’s driving me mad!!!
I want to be able to reset this somehow, how about me sending an SMS from MY number (the one in the settings of that tablet) to AVAST saying that I want everything canceled? Is that possible? This would be great, even thou I’d have to PAY for that sms I am still willing to do that to get rid of this thing.
This whole service isn’t that well thought out, and this is something that annoys the hell out of me.
How do I make it stop?? Is there any Avast representative that can help me with this?