The Athletics released Armenteros on Monday.
Armenteros cleared waivers and was outrighted to Triple-A Las Vegas by the Athletics on Thursday, Francys Romero of MLB.com reports.
Armenteros was designated for assignment by the Athletics on Tuesday, Martin Gallegos of MLB.com reports.
Armenteros was optioned to Triple-A Las Vegas on Sunday.
Armenteros, RotoWire's No. 3 prospect in the Athletics organization, is slashing .224/.360/.449 with 16 extra-base hits (nine doubles, one triple, nine home runs), 19 RBI, 31 walks, five stolen bases and 30 runs across 189 plate appearances with High-A Stockton.
Armenteros will make his full-season debut with Low-A Beloit on Monday.
Armenteros is opening the season in extended spring training, MLB.com's Mike Rosenbaum reports.