A trust is an OpenStack Identity extension that enables delegation
and, optionally, impersonation through keystone. See the
user
guide on using trusts </user/trusts>.

Removing Expired Trusts

In the SQL trust stores expired and soft deleted trusts, that are not
automatically removed. These trusts can be removed with:

$ keystone-manage trust_flush [options]

OPTIONS (optional):

    --project-id <string>:
                To purge trusts of given project-id.
    --trustor-user-id <string>:
                To purge trusts of given trustor-id.
    --trustee-user-id <string>:
                To purge trusts of given trustee-id.
    --date <string>:
                To purge trusts older than date. If no date is supplied
                keystone-manage will use the system clock time at runtime.