Prepare phone for repair

[Mahler]

Hi. 
I am due to return my iPhone 12 mini for repair. A faulty camera. Everything else is working fine. I asked the guy at O2 if I needed to turn off my Lock Screen passcode and face recognition settings and he said no - but looking at the 02 site it says to turn of passcodes. 

which is correct?

Also

Do I leave the SIM card in the phone or take it out and keep it!
What about the stored passwords on my phone for websites/apps and the likes. Should I delete them. 

Should I delete email accounts and any other accessible app  if the phone has the lock password deactivated?

many thanks in advance. 

[Cleoriff · Accepted solution]

@Mahler 

Everything you need to know is here https://www.o2.co.uk/help/device-and-sim-support/device-repairs 

[Mahler]

Thank you Cleoriff. 
Looks like I will have to delete my emails , messages and a few private things that become accessible with the screen lock off.