Here's a simple solution in Excel 365:

If your text is in cell A2,

then this formula:

=LET(x,MID(A2,SEQUENCE(LEN(A2)),1),CONCAT(IF(UNICODE(x)>1487,x,"")))

will remove the diacritics from the text

for example:

before:  בְּרֵאשִׁית

after: בראשית