I have a few problems.
First; my friend sent me a mail in-game but when I opne my mailbox it doesn’t show up there.
Second; I want to delete my starter account (WoW2) but I can’t do anything about it.
And for the last issue someone sent me a guild invitation but I can’t see it, he says that my account is free-trial but it doesn’t, in fact I’m 30 lvl right now. How can I solve all of these problems, can someone help me?
You should he able to remove a starter account here
https://eu.battle.net/support/en/help/product/wow/181/878/solution
The mail will be the same issue with the system thinking you are a starter account. You could try changing your password which would force the system to update. You can always change it back again afterwards