Few simple tweaks here to clear flash player cookies, technically..,
Right click inside display screen -> Settings
-> Adobe Flash Player Settings 
-> Click icon shown in the image (Folder with green arrow)
-> Let 'Never Ask Again' not ticked
-> Move the pointer to left (extreme )
-> Click OK (information will be removed message)
->Close
Exit and close all open web browser windows
Open web browser and log again, go back to flash settings but move this time the slider back to a middle position & Close
Now your flash cookies are cleared.
Right click inside display screen -> Settings
-> Adobe Flash Player Settings -> Click icon shown in the image (Folder with green arrow)-> Let 'Never Ask Again' not ticked-> Move the pointer to left (extreme )-> Click OK (information will be removed message)->CloseExit and close all open web browser windows
Open web browser and log again, go back to flash settings but move this time the slider back to a middle position & Close
Now your flash cookies are cleared.