removing metadata from .webm file

[giogi]

remove metadata from .webm file
how do i do that?
when i click on the right of the file and then click properties. and then "details" and then "remoove properties and personal information " then i get this: http://prntscr.com/iz414h
it says that i need admin permission to do that. but i am the admin.
so, is there a way to open properties as a true admin or some program that could do that for me?

thanks

 

[rgd1101]

so did you click continue?

 

[giogi]

so did you click continue?

yes, and it does not solve the problem 🙁

 

[rgd1101]

On the screenshot, the title, subtitle, rating, tags, comment is blank. so wwhat do you mean it not remove?

 

[giogi]

On the screenshot, the title, subtitle, rating, tags, comment is blank. so wwhat do you mean it not remove?

i want to remove its creation date. that is, to change it
http://prntscr.com/iz9bm0