Jeh-reh-mee-el
* Jeh like the beginning of "jet"
* reh like the beginning of "red"
* mee like the beginning of "meet"
* el like the end of "angel"
However, there are variations, and some people might pronounce it as:
* Jer-eh-mee-el (with a stronger emphasis on the first syllable)
* Jeh-rem-ee-el (with a slightly different emphasis on the second syllable)
Ultimately, the best way to pronounce it is to ask the person who uses the name how they prefer to say it.