18 The former regulation is set aside because it was weak and useless

Read Hebrews 7:18 Using Other Translations

For there is verily a disannulling of the commandment going before for the weakness and unprofitableness thereof.
For on the one hand, a former commandment is set aside because of its weakness and uselessness
Yes, the old requirement about the priesthood was set aside because it was weak and useless.