Hi:
You should be able to boot from a USB flash drive as follows...
Turn on or restart the PC.
Tap the ESC key at the beginning of the HP welcome screen to get the menu of options.
Select the F9 boot options menu and from that, select the USB flash drive and press the enter key.
The PC should now boot from the flash drive.
If for some reason the Flash drive is not listed, go into the BIOS, enable Legacy Mode and disable Secure Boot, and boot from the legacy USB flash drive.
See this link for the settings to change.
https://support.hp.com/us-en/document/c03659945
BTW, this is a peer to peer forum, not HP technical support.
if the above steps don't work, I suggest you contact HP technical support in the country you live in for further assistance.
https://www8.hp.com/us/en/contact-hp/ww-contact-us.html