Sync Tasks: you can find deleted files in the recycle bin in the web interface.
Backup task: in the Mac Drive agent you select the backup task and there's a Restore button. Within there there is a Show deleted files check box.
How far back do these go? For sync tasks this is set in Drive Admin Console, but I don't know for backup tasks.
I prefer to use Carbon Copy Cloner to make bootable (when system disk) clones to USB, and use the safety net feature to keep deleted files until space is needed. Then Time Machine, and other version backups (Drive etc), are for short term file recovery should that ever [never really] be necessary.