Not sure what access you have in PrePurchasing? Or not sure why you even have access to PrePurchasing? Use the following page to determine which groups you have permissions to, and who you should contact to have them changed.

https://prepurchasing.ucdavis.edu/user/contact

Departmental administrators are the only ones with rights to modify permissions for specific departments. The help desk and PrePurchasing programmers cannot make these changes.