remove one accurance of letter in string python code example

Example 1: delete certain characters from a string python

for char in line:
    if char in " ?.!/;:":
        line.replace(char,'')

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)