Since Windows 8 installation is done by you and you are in command, you are well equipped to try the AOMEI One Key Recovery (still in beta-testing) as suggested by SIW.
As mikiep has pointed out, if your Windows 8/8.1 is an upgrade edition, you may still require the original Windows 7 installation should it become necessary to go through a reinstall - ex.- HDD failed and needs to be replaced.
If your Windows 8/8.1 is a full pack, then no worries. Clean your HDD, install Windows 8/8.1 and go ahead with AOMEI One Key Recovery.
I would now suggest this course of action:
Users in the United States can now request a set of backup discs containing the factory-installed operating system as well as the Resource DVD which contains device drivers and utilities specific to the system. Requests are limited to one (1) set of backup discs per system purchased.
The backup discs requested must match the operating system that was factory installed on the original order.
Dell Media Recovery Options and the Request Backup Discs Form | Dell US
https://www.dell.com/support/diagnostics/us/en/19/nondiagnostichome
Even if you are not in United States/Canada you can talk to DELL Technical Support and make a request. Usually they oblige. I got the reinstall disk from DELL India without using any influence.(My daughter works for DELL. But they do not know that.
It was only when they wanted to courier it to me, I told them to hand it over to my daughter in the same building.)
Once you have got it, you can confidently remove even the original OEM Dell recovery partition, clean wipe the HDD and go ahead with a clean install with even your upgrade Windows 8/8.1 and use the AOMEI One Key Recovery without fear or favour.
Let us know how it went. ( Please don' t be in a hurry. Try and get the DELL Install media. Usually they ship it the same day and you will get it in a day or two.)