21.5" iMac desktop computer. (Polesworth B78)

Bought myself a new computer so wish to dispose of the old one. It is an iMac desktop computer with a 21.5" screen with a magic keyboard and mouse. I have carried out a factory reset so all my data is cleared. The screen now shows the introduction message with instructions of how to proceed set up. It is 13 years old and may not be compatible with some up to date software.