Tempdb datafile initial size

Hi,
I have tempdb datafile initial size setup for 30GB. That consumed lot of disk space. I am receiing out of disk space issue. I want to reduce initial size to 500mb. 98% free space available in this data file.

I tried to change initial size through db properties, alter database modify file, shrink database but no success.

Is there any way how to change tempdb datafile initial size to some lower value?

Thanks