Q: What can they see on my phone?

My phone was recently stolen and I want to know what they can see on my phone.

I did not have a passcode and blocked the phone straight away.

This means they can see all my pictures and all the information on my phone.

Is there any way for me to delete any apps on it using my iTunes account or somethng.

iCloud was not switched on.

I don't want then to see pictures or go through whatsapp conversations. :\