Update not completed [Verla 4.2 on XA2 Ultra Dual Sim]

I started the download of Verla update. Download was completed and I started the update process. Phone switched down. I entered password and got the message that updated failed and that I should try to try later again. Now, after reboot, in the settings/update page, notifications says “update is being prepared”, then I can start download the update, but I then get the message “waiting for connection”. I tried several times but always the same problem.
Question: is there a possibility to delete the already downloaded update file(s)? Any other idea how I can reset and start update anew?

See here