The Angels have a policy of not announcing minor league releases, so about all you can do is wait for Baseball America and other outlets to ferret out the information.
In their April 1 Minor League Transactions article, BA reported these releases:
RHP Rafael Flores, RHP Jon Plefka, RHP Brian Rogers, LHP Kevin Ferguson, 3B Ludwig Glaser, OF Jeremiah Luster
This is the time of year they start handing out pink slips, so if I see releases posted anywhere else I’ll let you know.
Elsewhere, I saw that the Pirates reassigned former Angels property Chris Bootcheck to their minor league camp, and that the Royals released Joel Peralta. Looking at the Minor League Transactions page, other former Angels include RHP Steve Green released by the Red Sox, LHP Kelly Shearer released by the Marlins, OF Chris Walker released by the Phillies, and RHP Ben Grezlovski released by the Nationals.