Slicing to a file

[Liquid_Ocelot]

And removing the for loops in this case just displays the outfile with no text. Really stumped to what I am missing

import sys
print(" *** Truncating File Copy ***")
infile_name = input("Please enter the name of the file to copy: ")
outfile_name = input("Please enter the name of the new copy:  ")
infile = open(infile_name, 'r+', errors = 'ignore')
outfile = open(outfile_name, 'w+')
newList = infile.readlines()
def omit():
       omitline = int(input("Omit how many lines from the start:"))
       newList[omitline:]
def omit2():
       omitline2 = int(input("Omit how many lines from the end:"))
       newList[:omitline2]
omit()
omit2()
outfile.write(infile.read())
infile.close()
outfile.close()