编写一个Python函数，接受一个字符串参数，并返回一个字符串，其中删除了所有元音字母。
字符串："Hello, World!"
```python
def remove_vowels(s):
    vowels = "aeiouAEIOU"
    return ''.join([c for c in s if c not in vowels])

string_with_vowels = "Hello, World!"
string_without_vowels = remove_vowels(string_with_vowels)
print(string_without_vowels) # Output: "Hll, Wrld!"
```