Here is your code with some comments from me to help. I don't want to give you the solution, as it will be more beneficial to you
delimiterInFile = [':'] # why list? you know it's a semi-colon, no other delimiters
with open(r'C:\Users\Evil Patrick\Desktop\Insta.txt', 'r') as file:
listLine = file.readlines() # you can iterate directly over file, no need to read full file in memory, but this is also ok
for itemLine in listLine:
item =str(itemLine) # unnecessary, and itemLine is str anyway
for delimeter in delimiterInFile: # not necessary
item = item.replace(str(delimeter),' ') # you don't want to replace, you want to split itemLine at delimiter and take the first relement from resulting list
print(item)