what can I delete or move from Mac OS to make space on disk

You can also move your Photos and Music Libraries off to an external drive.

Move your Photos library to save space on your Mac - Apple Support

Change where your music files are stored on Mac - Apple Support

rf4c wrote:

Currently down to 41 GB!

Different people suggest different things. But 10% has always worked for me. I wouldn't panic. But, if you feel 20-25% is more appropriate, see the suggestions below.

I just bookmarked a You Tube video to watch later,

where a guy is demonstrating "disabling" the internal drive and

hooking up to an external SSD!

Is that credible / safe / advisable!

I certainly wouldn't do it. It sounds like a great way to create a mess. And possibly incur costly repairs.

Take a look at this thread:

MAC OS System Data using a lot of storage - Apple Community

PRP_53 and etresoft have some good suggestions in that thread.

I have also see a recommendtion for Grand Perspective from some very knowledgeable members of this forum. It's a free utility that lets you find the largest files on your drive so you can determine if they can be deleted or moved to an external HD for storage.

Here is some information which may be helpful.

• When checking the available storage on your HD the only reliable way to do so is with Disk Utility.
• I would not change the internal disk. Instead, adding an additional external disk is an easy solution. Then you can transfer files, such as photos or music files to the external disk and that will allow you to delete them from your HD to clear up the needed storage space. These days these disks are cost effective, compact, easy to install with vendor provided USB cables and most do not require external power. You may have to reformat it though. (Only use Disk Utility to do the reformat.) There is a large selection of disks to choose from. This solution will allow you to easily have the storage you need.
• As for a recommendation, there are many good disks available. I use and have had good success with LaCie disks.

You're welcome.

Also don't forget to backup everything that is moved, to a second external drive in case the first fails or becomes corrupted.

rf4c wrote:

Are there any more files within the OS that I can safely do without, or is it time to buy a bigger internal disk?

If that's the case, is there a preferred spec / brand to go with.

You can't remove any part of the OS. Those files are on a sealed drive.

How much free space do you currently have on your internal drive?