Exclude items from a Time Machine backup
You can exclude items from a backup to save space on your backup disk, or to exclude items you back up using another method.
Choose Apple menu > System Preferences, then click Time Machine.
Click the Add button , then select one or more items. You can also drag items to the list. To remove an item, select it, then click the Remove button . For example, you can exclude system files or the Applications folder from Time Machine backups using Time Machine preferences.
The backup disk is automatically included in the list of items that shouldn’t be backed up.
Note: Excluded items still appear in Time Machine local snapshots.