MATL, 6 bytes
QJi-h)
Input is given as 1) number of elements to trim from the start; 2) number of elements to trim from the end; 3) array. Explanation
Q % Implicit input (1). Increment by 1, since MATL indexing is 1-based.
Ji- % Complex 1i minus real input (2). In MATL, the end of the array is given by `1i`.
h % Concatenate indices to get range-based indexing 1+(1):end-(2).
) % Index into (implicitly taken) input array. Implicit display.