Hi Malcom!
Unfortunately there is no such ability at the moment. The only workaround is to change the person's password, login as him/her and then delete the dashboard.
I think there was something about the dashboards on the Genesys Cloud roadmap and there are ideas on the Idea lab.
This is definitely an oversight in my opinion that even the master admin cannot delete or change dashboards created by other users.
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Riitta Richard
Advania Finland Oy
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