08-07-2020 11:25 - edited 08-07-2020 11:26
If you want to leave and keep your mobile number you need a PAC code, to get your PAC code, text PAC to 65075.
If you just want to end your contract, and are happy to loose your number, you need a STAC code. Text STAC to 75075
O2 should reply with any early cancellation charges if applicable
on 08-07-2020 11:27
Hope this helps.
on 08-07-2020 11:41
The cancellation process is described in full here Guide: Cancelling Your Contract
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)