Once created approval channels can not be deleted, however the approval criteria can be updated or the criteria can be completely removed.
You need to be a system admin to be able to edit an approval channel.
HOW IT WORKS
STEP 1: Go to the settings area
Settings --> Select the module --> Select the Legal Entity (unless the approval channel you want to edit is created at the global level)
STEP 2: Select the approval channel you want to edit
Click on the pencil icon to edit / remove the criteria from the approval channels.
STEP 3: Update or remove the criteria (amount and / or list) and save the changes
Clear the amount criteria, by clicking on the 'Clear'
Clear the list criteria, by clicking on the 'x' sign on the list
STEP 4: Update or remove the approvers from the approval channel and save the changes
4.a) Expand the approval channel by clicking on the arrow next to the approval channel name.
4.b) Click on the pencil icon next to the approvers
Select the approver(s) and move them to the available approver columns, by clicking on the '<' sign and save the change.