The six cells A4, B4, C4, C5, A6 and E6 form a UVWXYZ-Wing.
The five cells A4, B4, C4, C5 and A6 are an Almost Locked Set (ALS) that is linked to the bivalue cell E6 through the value 3, so if the value 9 was eliminated from all six Wing cells then the remaining value 9 of E6 leaves just four values to fill the five ALS cells, which is invalid; so 3 is "locked into" these six Wing cells, hence 9 can be removed from cells which see all 9's in the Wing.
Therefore we can remove B6-9, E4-9.