Amazon does not let you permanently delete purchase history from your account
You can archive orders to hide them from the main order list
Sign in to your Amazon account
Go to Your Orders
Find the order you want to hide
Select Archive order
Confirm the action
To view archived orders, go to Account & Lists
Select Your Account
Open Archived Orders
If you want to reduce visible order activity, you can also:
Delete browsing history from Your Browsing History
Remove items from your wish list
Clear search history in the Amazon app or website
Use a separate account for future purchases if needed