Mega strange folders & files created

Hi,

Some time ago I installed L.O. Portable 3.3.0 on USB.
It seems to have created a big troop of files & folders in:
G:\PortableApps\LibreOfficePortable_3.3.0\LibreOfficePortable\Data\temp\svp.tmp

I cannot delete them because they all contain "forbidden" characters like /\:*?"| and more of that.
Windows file manager says: 'Cannot delete file: Cannot read from the source file or disk'
Also their filesize and dates of modification are absurd (some are of 1601/01/01 !)
Does anyone know how to delete them ?

(installation of L.O. 3.3.3 was seemlessly)

thanks