Delete older versions of the set of on-demand backups

Hello there I'm need to save some space on our policies

we are backuping a group of computers,
the Users do the backup on demand,
this backup needs to be stored indefinitely but we need to have only one run of each pc like the restorepoints on Veeam

I'm seeking for a little help on an some options

• to make an automatic script when the backup finishes successful
• to make a process that weekly deletes the older versions

Thank you for your help