How much can I deduct as expense for a $767 compensation in a form 1099-MIS? I also received a W2 from another source in a much higher amount, Both as Dental hygienist.

In the link to the IRS tax tips says "You can deduct most miscellaneous expenses only if they exceed two percent of your adjusted gross income." If I have $100 in expenses but my AGI is $25000, can I still deduct the $100 even if it is less than 2% of my AGI?

You can deduct as expenses as much as you have against the $767 income from the 1099-MISC.  Meaning you could have more expenses involved that the income earned.

These expenses needs to be documented and be part of earning this income.

The following IRS information may e helpful:

https://www.irs.gov/newsroom/reduce-your-taxes-with-miscellaneous-deductions