Can I downgrade Catalina to El Capitan using a flash drive?
109386
How do I create El Capitan installer on a Catalina (or post-El Capitan) installed Mac for use on USB boot installer
46655
OS X El Capitan Installer.app has crippled my Mac Mini
3612
Can I downgrade to Mavericks after installing Yosemite (beta/developer preview)?
21236
How can I delete everything from my MacBook Pro before selling it?
8421
Multiple Operating Systems or ISO's Bootloader for a USB Stick?
91582
How do I get a live-USB to use a partition for persistence?
32069
Can the Mavericks install binary be shared between two different apple accounts?
2136
How to roll back Ubuntu to a previous version?
89166
How to downgrade Kernel
11780
How can I download the macOS Big Sur installer on a Mac which is already running Big Sur?
23773
How can I make a macOS Mojave bootable USB installer in Windows 10?
60029
Which macs are compatible with OS X 10.11 El Capitan?
116657
Install an older OS X version on an external volume
28172
I want to downgrade from Yosemite 10.10 to Mavericks or previous operating system
56653
iMac won't boot off of Mavericks USB when downgrading from Yosemite
84511
Re-use Mavericks install file
4251
How do I get my Mac to boot from an Ubuntu USB key?