How to revert from Windows 10 to preinstalled Windows 8.1 using the original WINUCRD.WIM file saved on an external HDD??

I have an HP 250 G3 laptop which originally came with Windows 8.1 with Bing preinstalled and a recovery partition. When Windows 10 update came out, I updated to Windows 10 and soon after this I deleted all the original partitions (together with the recovery partition) and did a clean install of Windows 10. Before I did this, I saved the recovery partition content to an external HDD and now I have the file (recovery)-(Windows RE+_CNBPR2.FLG+lang.ini+TypeList.txt). WindowsRE folder contains winUCRD.wim file, which contains Program Files, Program Files(x86), Program data, sources, Users, Windows, and DELETED folders. Since Windows 10 has never worked properly on this laptop (slow performance), I would like to revert to my original Windows 8.1 with Bing using the aforementioned files and folders in order to keep my preinstalled licence key. IS THIS POSSIBLE AND HOW TO DOIT?

Look at this article, it may help:
Transferring HP Recovery Media to Bootable USB Storage

However, I think that it's not the only possible way. You should be able to (re)install Windows 8.1 from the typical media, like a USB bootable drive with Windows 8.1 ISO, you only need to download the appropriate version (Pro or Single language) and create such USB. All you miss this way are the manufacturer's drivers, but they can be downloaded from the support page anyway, maybe even more recent than in your WIM file. As for activation, it should be already stored in Microsoft activation database since Windows 8.1 pre-installed on your PC has been activated first time. You may use a generic key, unlike the retail OS which needs a unique key.