If you would like to set for an limited access to your PayPal account just for contractors and web designers to use, then you would do the following. This only works if you have a "Business" account.

1. Log into Paypal
2. Click Profile
3. Click "Muli-User Access
4. Click "User"
5. You may be asked to confirm your identify with your full bank account number.
6. Type in the "User Name", pick an user id, pick a password.
7. Checkmark "View Profile" and "Edit Profile'
8. Click "Save"
9. Pass the choosen username and password to the contractor.

Now your contractor has access to set things like tax rate, but not withdraw funds.

If you want your contractor to set PayPal shipping, checkmark that in step 7. But note that when you checkmark that, PayPal also checkmarks other privileges like "Send Money".

My recommendation is to keep your PayPal password private and tell your contractor to tell you how to set the setting yourself.