VSSGP | Variational Sparse Spectrum Gaussian Process toolkit | Machine Learning library

Any idea what I am doing wrong?

Project Administrator Group owns the highest permissions in Team Project level. So the project permissions (Project Settings=>Permissions) about that group is not editable:

It's by design that Project Administrators will always have the permission to delete team project.

Except the Project Administrators group, other groups's permissions are editable, see:

1.So it you want to add one member to Project Administrator group, he's permission about deleting project can't be removed.

(No matter which way we use, Web page, Azure Devops Rest Api, az devops cli command or what, none of these would work since it's by design)

2.And if you do want to give one member most permissions the Project Administrator should have but except Delete Team Project permission, you can try creating a new group (In project Settings=>Permissions page) and give the group all permissions except Delete Team project permission, something like that:

You also need to do extra job to give the group necessary permissions in Pipeline Security(see pic below), Repos permissions(Project settings=>repos=>repos) ...

Then add the member into this Custom Group instead of default Project Administrators Group.