please provide the output of
oc get serviceaccounts -o json

{
    "apiVersion": "v1",
    "imagePullSecrets": [
        {
            "name": "delete-admin-dockercfg-553lq"
        }
    ],
    "kind": "ServiceAccount",
    "metadata": {
        "creationTimestamp": "2017-11-06T16:05:33Z",
        "name": "delete-admin",
        "namespace": "default",
        "resourceVersion": "1512",
        "selfLink": "/api/v1/namespaces/default/serviceaccounts/delete-admin",
        "uid": "516d04f9-c30c-11e7-a08a-6abe92e081f3"
    },
    "secrets": [
        {
            "name": "delete-admin-dockercfg-553lq"
        },
        {
            "name": "delete-admin-token-l1b05"
        }
    ]
}

also not that the proper command to add delete-admin to the cluster role is not:
oc adm add-cluster-role-to-user system:service:accounts:default:delete-admin

but it is:
oc adm policy add-cluster-role-to-user delete-projects -z delete-admin


This does not allow me to delete a project either though.

WOW, when was -z added?! That's awesome! The docs still recommend system:serviceaccount:<project>:<sa-name>. [1]

https://docs.openshift.com/container-platform/3.6/dev_guide/service_accounts.html#dev-sa-user-names-and-groups

You are logging in as the SA incorrectly.  The correct way is:

> oc login --token=$(oc sa get-token SA_NAME -n SA_NAMESPACE)

This is clear from the error message:

> Error from server (Forbidden): User "other-admin" cannot ...

If you were logged in as the SA it would say:

> Error from server (Forbidden): User "system:serviceaccount:SA_NAMESPACE:SA_NAME" cannot ...

You can use `oc whoami` to tell what user you are logged in as.

Ok I have also reproduced and using:
> oc login --token=$(oc sa get-token delete-admin -n default)
> oc delete project myproject 
worked.
Closing NOTABUG

Thanks! That did the trick!