How do I get enough space on my startup disc to update

Hello!

The only way to get more free storage space is to delete files off of your computer. You can follow the steps in the link below in order to figure out what is taking up space and free it up.

How to free up storage space on your Mac: https://support.apple.com/en-us/HT206996

Let me know if this helps!

You do not say what exact Mac you have...

If it is an older Mac and user upgradable you can simply buy a larger hardrive.

Storage - OWC

Boot clone https://discussions.apple.com/docs/DOC-10081

How to use Time Machine to back up or restore your Mac: https://support.apple.com/en-us/HT201250

Throw stuff away is always the most direct way, but is not the ONLY way.

You could move some files to an external drive. For example, if you have an extensive music playlist, do you need ALL those tunes to be portable (and on the boot drive on your Mac)? You could move your music library to en external drive.

Traditional external drives are big clunky things that are not portable. But recently this device has become available, and runs at SSD speeds:

SanDisk SDSSDe60

shown about actual size 2 by 3.4 inches by 1/3 inch thick

has a 6-in USB3 cable with a tiny USB-C adapter included -- Bus powered

also sold at the Apple online store and in many Apple stores.

I hope everything works out!