remove last empty line from pandas to csv using lineterminator

I'm not able to reproduce your issue, but it might be the case that your strings in the dataframe contain trailing line breaks. I'm running Pandas 0.23.4 on linux

import pandas
print(pandas.__version__)

I created what I think your dataframe contains using the command

df = pandas.DataFrame({'colA':['A'], 'colB': ['B'], 'colC':['C'], 'colD':['D']})

To check the contents of a cell, you could use df['colA'][0].

The indexing I needed to grab the first and second columns was

df.iloc[:, 0:2]

and the way I got to a CSV did not rely on lineterminator

df.iloc[:, 0:2].to_csv("report_csv.txt", encoding='utf-8', index=False, header=False)
df.iloc[:,2:].to_csv("report_csv.txt", encoding='utf-8', index=False, header=False, mode='a')

When I run

with open('report_csv.txt','r') as file_handle:
dat = file_handle.read()

I get 'A,B\nC,D\n' from dat.

To get no trailing newline on the last line, use to_string()

with open('output.txt','w') as file_handle:
    file_handle.write(df.iloc[:, 0:2].to_string(header=False,index=False)+"\n")
    file_handle.write(df.iloc[:,2:].to_string(header=False,index=False))

Then we can verify the file is formatted as desired by running

with open('output.txt','r') as file_handle:
    dat = file_handle.read()

The dat contains 'A B\nC D'. If spaces are not an acceptable delimiter, they could be replaced by a , prior to writing to file.