Migrated old Macbook to a new one. Now hard drive is full.

Continued from my previous reply.

Troubleshooting a Full Mac Hard Drive:

Here is how to start over....

Restore Once More or Reinstall Anew:

A. Restoring the macOS:

Go Here: How to Reinstall macOS from macOS Recovery - Apple Support

Important: First, Back Up your Mac:

Prior to all of this, do you Create a Time Machine backup of your Mac? If so restore your Mac from it. If not, then take this as a learning experience, knowing to always create a backup of your Mac, prior to making any major changes to it (i.e. new install). Then, use Migration Assistant to transfer as desired.

transfer your information to Mac from another vomputer or Device - Apple Support

B. Reinstalling the macOS Anew:

See if this Site Helps: How to Reinstall the macOS Anew - No TMB Prior to Upgrade - User Tip. Format the hard drive with the applicable macOS, on step D.

In Depth:

Pretty much, it is a matter of:

1. Erasing: and formatting your hard drive to APFS
2. Installing: [the applicable macOS] via a USB Bootable Installer
3. Restoring: info from a Time Machine Backup, using Migration Assistant

Blazey2 Said:

"Migrated old Macbook to a new one. Now hard drive is full.: In my haste to use my new toy, I migrated all my information from my older Macbook Pro to the new MacBook Pro. The issue is the hard drive is nearly full and I am having trouble running Photoshop as the scratch disk is full. [...]Are there any good options to remove the older Mac info and just start over? "

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Troubleshooting a Full Mac Hard Drive:

Here is what to try....

Boot into Safe Mode [Hold Down: shift key upon boot] and then perform the following:

A. Remove: Login Items:

See if Safari and/or Chrome are Login Items. If so, remove them as such and then restart the Mac, seeing if it/they no longer load(s) at login.  Go Here: Change Users & Groups Login Items preferences on Mac - Apple Support.

B. Uninstall: Security Software:

Any Security Software installed on your computer? If so, uninstall it. Use the Uninstaller for to do so, getting the Uninstaller directly from my Developer’s site, as getting it else where may result in Malware or Spyware being installed. If you are uncertain which to download, then as the Developer. What is it doing is running you through VPN (Virtual Private Network), and your location is seen elsewhere — perhaps a location that this site is inaccessible to.

C. Scan: your Mac for Malware: 

Use MalwareBytes for Mac --- This is software that searches for malware/adware. So, scan with it and then remove what is found. Once removed, uninstall MalwareBytes for Mac. Then restart the Mac.

Downloads:

1. Malwarebytes Anti-Malware for Mac
2. Malwarebytes Uninstaller

D. Clean: Space:

Delete Unneeded, Large Files:

Remove all unneeded files from your TV and Music Libraries. Full-Movies take up 2-4GB typically, and a bunch of those would take up a load of storage, ideally. So, if you have any movies that are not needed, then delete them.  Virtual Machines can be in the double and triple digits of GBs of data.

E. Clear: Temporary Internet Files:

• Cookies perform remembrance of certain site-entered data.
• Cache keeps a snapshot of the last time you visited a site.
• Go Here: Clear the History and Cookies from Safari on your iPhone, iPad, or iPod Touch - Apple Support

Continue to my following reply.