I cannot login to my iMac Pro forgot password

Read the contents of this article.

https://support.apple.com/en-gb/HT202860

Choose a password you can remember, you should be able to set up password hints.

Write the password down somewhere and store in a safe memorable location.

If you can't start up from macOS Recovery

If your Mac can't start up from its built-in macOS Recovery system, it might try to start up from macOS Recovery over the Internet. When that happens, you see a spinning globe instead of an Apple logo during startup: 

To manually start up from Internet Recovery, press and hold either of these key combinations at startup:

• Option-Command-R
• Shift-Option-Command-R
• Learn more

If startup from Internet Recovery is unsuccessful, you see a globe with an alert symbol (exclamation point):

If you see the globe and alert symbol, try these solutions:

• Make sure that your Mac can connect to the internet. If you're not prompted to choose a Wi-Fi network during startup, choose a network from the Wi-Fi menu , if available.
• Press Command-R at startup to try using the built-in Recovery system instead of internet Recovery.
• Connect to the internet using Ethernet instead of Wi-Fi, or vice versa.
• Connect to the internet from a different Wi-Fi or Ethernet network. Your network configuration might not allow the internet access that macOS Recovery needs.
• Try again later, because the issue might be temporary.
• Start up from another disk or volume, if available, or use a bootable installer to reinstall macOS.

If you still need help, please contact Apple Support.

Reset Computer Password 

Intel Computer

1 - Restart computer and immediately hold Command + r keys

2 - Top Tool Bar >> Utilities >> Terminal

3 - Type resetpassword as one word and no spaces

4 - Press Return key

5 - Follow the prompts and remember the New Password