'Suppress' is the technical linguistic term; "drop" is used in the usual prescriptive grammars.

Also syncope: In linguistics, syncope is the deletion of phonemes from a word, or from a phrase treated as a unit; compare elision.
en.wikipedia.org/wiki/Syncope

... the case of disyllabic adverbial prefixes that **suppress the final vowel** before an augment or before an initial vowel in a verb stem (eg PAR-E-QHKEN for ...
lists.ibiblio.org/pipermail/b-greek/2003-May/021308.html

patterning like (Cáro)(lìne), **whose final vowel is null** (a ... skt, Npt, spt, where the added final coronal would suppress the release of the ...
www.cog.jhu.edu/pdf/Phonology and Phonetics.pdf

either a primitive root LON haven, or LOD- narrow path, pass [Etym; the -l- **becomes a sycope and the final -d is dropped** in long S names]; the region is a ...
www.quicksilver899.com/Tolkien/SILM/SILM_CE.html

**These verbs all drop the final vowel** before objects (nouns or pronouns). Ganê drops the. final -nê before noun objects. Of the three, only barÏ is commonly ...
www.humnet.ucla.edu/humnet/aflang/hausarbaka/Video_Files/M1...