Use .drop(1).
This has the benefit of returning a new Array with the first element removed, as opposed to using .shift, which returns the removed element, not the Array with the first element removed.
NOTE: It does not affect/mutate the original Array.
a = [0,1,2,3]
a.drop(1)
# => [1, 2, 3]
a
# => [0,1,2,3]
And, additionally, you can drop more than the first element:
[0,1,2,3].drop(2)
=> [2, 3]
[0,1,2,3].drop(3)
=> [3]