how to remove or pop a letter off of a string in python code example

Example 1: take off character in python string

s = 'abc12321cba'

print(s.replace('a', ''))

Example 2: python remove letters from string

string = "abc123"
# Method 1
''.join(char for char in string if char.isdigit())

#Method 2
import re
re.sub("[^0-9]", "", string)