If I understand correctly, you have specific users of Serv-U that you want to have the ability to manage user accounts. If this is the case, then you will need to create Serv-U accounts for your computer accounts management team and grant them the proper level of administrative rights to allow them to maintain other user accounts. If they are configured as Domain Administrators, then they will be able to modify any setting within that domain (including other user accounts). This is the easiest way to get this working but may not be desirable because of all the other options available for configuration.
Instead, you may want to set them up as a group administrator. This will restrict their admin rights to ONLY be able to modify values with their group and users that are a member of the group. The downside to this is that every other account would need to be a member of this group so that group admins have the ability to modify those accounts. Any account that isn't a member of the group cannot be managed by a group administrator.
If you go this route, you might find it best to create a group for your "computer accounts management team" and make this group a "Group Administrator". Place all the new Serv-U accounts for your mgmt team in this group. Create a second group for all the users you want them to be able to manage. Add all applicable user accounts to this group (including your new new mgmt team accounts - users can be members of multiple groups).