I’m afraid it will renew itself and charge it to my bank account, in which I don’t have enough funds and it will overdraft.
Does Avast renew itself? Or do I have to renew it manually?
If it does renew itself, how can I cancel the renewal?
No avast doesn’t auto charge your card.
Uninstall the avast paid version that you have and install the free version, when you have sufficient funds you can upgrade.
Free AV: - http://files.avast.com/iavs5x/avast_free_antivirus_setup.exe
Also note that renewal orders get 30% off. So before uninstalling, note your avast customer ID in the Subscription information window. You will need this when ordering the pro version to get your renewal discount