Python3: Looping over a string

I would like to program something in python3 and do not understand where my mistake is.

seq = ('1gnadutnpawihv\n  casc341')

check = ('0','1', '2', '3', '4', '5', '6', '7', '8', '9')

while i < len(seq):
    for j in range(len(check)):
        if seq[i] == check[j]:
            seq=seq.replace(seq[i],"")
            

seq=seq.replace("\n","")
seq=seq.replace(" ","")

seq

I want to eliminate the characters "\n", " ", and all numbers from 0 to 9 from the string seq with the replace function. Now I want to iterate over the seq and compare each character with each character of the tuple check and detect the numbers 0 to 9 and replace them afterwards with nothing.
The replacement method works for "\n" and " ", but not for the numbers.
The output is simply:

'1gnadutnpawihvcasc341'

Why doesn’t it work?

>Solution :

The problem was with the outer while loop. Instead of fixing it I removed it because it was redundant. I also removed the \n and spaces in the same loop:

seq = ('1gnadutnpawihv\n  casc341')
check = ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '\n', ' ')

for j in range(len(check)):
    seq = seq.replace(check[j], "")

print(seq)

Output:

gnadutnpawihvcasc