The A minor open chord should be played with the low E (6th string) muted/unplayed.[br][br]By convention when we play a chord, we strike the root note of the triad of notes comprising the chord as the bass or lowest note in the chord. So the primary note/string struck first when strumming Am should be the A on the (5th) string.[br] [br]The open form of the Am chord already contains two played E notes an octave apart, one a fretted note on the D string the other the open high E (1st string). Accidentially or mistakenly playing the low E won't turn the chord into a total train wreck as E is one of the three notes of the minor scale (ACE) comprising the chord, but striking it first instead of the root makes the chord sound off to the attuned ear. [br][br]Recapping. You should play that form of Am without striking the 6th string or with it muted.