I am trying to keep the approval option for Purchase Orders but get rid of any hierarchy and allow anyone to approve them. Does anyone know how I can do this?

Isn't how that works out of the box? That's how it works for us. It's just like any record that can be approved etc.

did you turn on the approval routing accounting preferences? if so then you can use a workflow to run approval process in any way you want.

and why to have approvals at all?

So I got it to work. With approval routing on and a workflow allowing anyone to approve. The reason why is that we first enter $0 POs for a purchasing team. Then when prices get updated and purchases are we approve them and our warehouse team has a list for receiving. Does that make sense? I am sure there is a better way to do this but this wil work for us.

the process is a bit convoluted - why not let your purchasing team to raise the PO with updated price the do the proper approval as budgetary or finance control?