LeetCode: Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once.

My code works for all of the test cases so far, except [1, 1, 1, 1]. In that case, it is only going to [1, 1] and not removing the duplicate 1

def removedup(nums):
    for n in nums:
        if nums.count(n) > 1:
            nums.remove(n)
    return(nums)

removedup([1,1,2]) #works
removedup([1,1,1,1]) #doesnt work