Help deleting back up files

[Bulldog VII]

Hi all

I'm running Catalina on the lastest update, I have an external harddrive that Time Machine backs up too, this is now full & I need to delete the content, however it's nearly 500gig & the empty bin takes about a day & then tells me I don't have the required access levels?

I seem to remember ages ago, if I restarted the iMac & held a certain key down it would empty the bin instantly?

Anyone help please & yes I have tried to google an answer

Ta

Phil

 

[Bulldog VII]

Sorted now, downloaded the Western Digital program, took seconds to empty!