How to do a "factory reset" and restore my device to as-new miui.eu?

I have a brand new Mi11, Flushed the latest MIUI.EU (xiaomi.eu_multi_MI11_V14.0.8.0.TKBCNXM_v14-13) and everything is working fine.
I just HAVE TO USE only once an app which is very system-intrusive.
I have to use it for a day and then want to have a fresh start for my phone with MIUI.EU.

So the question is simply - How would I preform the format/factory-reset?

Thanks in advance!