Suppose element pointed by some pointer is last node(tail),From the head node we traverse the entire list and reached the last node(tail).

So.it takes $O(n)$ times and some pointer manipulation time.

So final Time complexity is $T(n)=O(n)$

So.it takes $O(n)$ times and some pointer manipulation time.

So final Time complexity is $T(n)=O(n)$