If Macbook is backed up with Time Machine, can I delete files on Macbook to get more storage?

No. When the TM backup drive becomes full, then TM will delete older backups to make room for newer backups.

iCloud is not a backup. iCloud is only a file syncing service. If you make a catastrophic edit or deletion, then that will affect every other copy of that file on every other device which is syncing to iCloud. iCloud file syncing is a convenience to allow access to files on multiple devices....it is not a backup.

USB sticks are also not a good option for storing files since the quality of USB sticks is extremely poor, plus they can be easily lost or misplaced. Many of the USB sticks I have tested will have bit flips occur which can damage the data within the file or even corrupt the file system where so you won't be able to access the files on the USB stick.

If you want to store files on external media, then get an external USB3 SSD or hard drive (the latter will be slow). And make sure that TM is configured to back up the data on that external data drive as well.

Drterrib wrote:

But still not clear on the answer to my question.

I thought "No" was pretty clear. A backup means you have a backup copy (aka a second copy) of that file. If you only have a single copy of a file, then you have no backup.

All I can say is you are trying to play games with the backups which will ultimately result in you losing an important file at some point. If the data is not important, then go ahead with playing games with the backups.

If, however, you value this data, then you need to have more than one copy of that data on more than one drive. The more important the data, then the more backup copies you should have of that particular data.

With the more recent Macs, there are a lot more new ways to permanently lose access to your data due to all the new hardware, software, and security changes. Backups are more important than ever before.

I know eventually the TM will begin to delete files but my understanding is that will not happen until the drive is full.

That is what is supposed to happen. But you may not know or realize when the drive becomes full since TM takes care of everything behind the scenes. I'll repeat again....if you only have a single copy of the data, then if anything happens to that drive, that data will be permanently lost. Just how important is this data to you?

Backups are meant to be a second copy of the data (even a third or fourth copy). Backups are not meant to contain the only copy of that data.

In the meantime, if I delete a file on my Macbook, can I open that file from the Time Machine should I need to?

Not directly. You would need to launch the TM app and locate the file you want through the Time Machine interface and restore it. Then you can open the restored copy.