[R] delete data row

[IRD]

  Dear All
I have data like this:
 > IR
       x        y
[1,] 5 2.865490
[2,] 3 1.454611
[3,] 3 2.258772
[4,] 6 1.476128
[5,] 4 2.771606
 > y.j
        y
2.865490
 >
and I want to delete data row in IR where y = y.j
How I can do.
IRD