@SNOW_22 

Go to dashboard and check audiences, remove users/groups/roles from specific dashboard

Another easy way is to go par_dashboard_permission table and remove the view/edit permissions for specific dashboards or set Share = 'false' 

I hope you appreciate the efforts to provide you with detailed information. If my response helped to guide you or answer your query, please mark it helpful & accept the solution.

Thanks,

Bhuvan