You should keep two (full) backups. When I do a new backup, I keep the previous backup. If something should happen during the new backup and it would be bad enough that you would have to do a complete hard drive restore you still have the previous back up.
If you deleted all backups and just started a backup and something would happen, you would not have a backup to use to restore.
I used to use Acronis and recently moved to Macrium. I bought a 4 license version as I have multiple PC's. I guess I could have used the free version, but I feel better having the full paid version.
I always do a full backup so that was not an issue for me. Where I worked, before retiring, I was a regional LAN/WAN Network Manager for a large portion of central US (basically everything west of the Mississippi to the Rocky Mountains). When we started converting field offices from "dumb terminals" to LAN's we initially did server backups nightly with a full backup on Monday evening, incremental backups on Tuesday/Wednesday/Thursday/Friday. We had all the data but with all the backup tapes (it was an SCSI tape system for backups) if a server required restoring, the tech had to make sure they did it in proper order. As it turned out it took longer to restore the server with this method. It was changed to a full backup every night and with only full backups, it avoided potential problems of restoring out of sequence, and with just one backup the server downtime was minimized.