Reset MacBook Air without admin account or command s
Solution 1:
If the Mac asks for a password before boot (just a password field, no user name) what you are encountering is the firmware password, see https://support.apple.com/en-us/HT204455
The procedure to removing the firmware password depends on the MacBook model, for all Intel MacBook Air models without a T2 chip (pre-2018) only Apple can remove the firmware password. You will need to visit an Apple Authorised Service Center and bring proof that you own the device(s).