I’ve got a Dell Latitude 5420 which I set a couple of years ago a bios admin password and a system password.  I’ve decided I no longer need them as I want to sell the laptop however I’m unable to remove them.  

I go into bios, into passwords, successfully enter the admin or system password, enter again on new password.  Yet still stays the same.  Even after ‘saving’ and rebooting the passwords still there.  
I’ve even tried changing the password from the bios - same issue on reboot old password is back. 

jo matter how I’ve done it and what steps it’s the same.  

any suggestions?   I don’t mind keeping the admin password as I can just give that on.  But the System password on every boot is too much so want to remove it but as above - won’t remove.  

any other tips to even just remove the system password?  Any way to flash the bios / bios recovery where system passwords can be wiped?