CiviReport: Cannot remove Contact ID filter
The same thing happened to me.  The Constituent Detail report is called from the Constituent Summary Report.  I ran the summary report and clicked on a contact to go to the detail report.  As an Administrator I accidentally updated the Constituent Detail Report.  It must have saved the contact ID used in the call from the summary report.  Every time I tried to use or call the detail report from then on it used the stored (saved) contact ID.

To solve the problem I deleted the Constituent Detail Report from the Contact Report area.  I then created a new report using the standard Constituent Detail Report as the basis.