allow to delete the selected account

[r10s]

not allowing to delete the selected account forces users to switch to another account after reviewing that an account can be deleted - then, in the list, they have to pick the correct account to delete, which can be challenging and is error-prone.

it is better to just allow deletion of the selected account (i think it was introduced for technical reasons)

todo:

• [x] show the delete account button unconditionally
• [ ] handle last account deletion
• [ ] update chatlist after account deletion

no priority :)