Below you can find an example how to remove a row from a text file using sed command and bash shell. Here is a content of our sample file:
$ cat example.txt 
AAAAAAAAAA
BBBBBBBBBB
CCCCCCCCCC
DDDDDDDDDD
EEEEEEEEEE
Next, we are going to remove a second row from the above example.txt file:
$ sed 2d example.txt 
AAAAAAAAAA
CCCCCCCCCC
DDDDDDDDDD
EEEEEEEEEE
Futhermore, we can also remove multiple rows from this file. For example let's remove all rows from 2 to 4:
$ sed 2,4d example.txt
AAAAAAAAAA
EEEEEEEEEE
We can also remove all lines matching a certain regular expression. In the next example we are going to remove line which contains at least one C character:
$ sed '/C/'d example.txt
AAAAAAAAAA
BBBBBBBBBB
DDDDDDDDDD
EEEEEEEEEE
To save the change into a existing file use -i option. This way the sed command will overwrite your original file:
$ sed -i '/C/'d example.txt
or simply redirect the output to a new file:
$ sed '/C/'d example.txt > example2.txt
Additional examples:

Remove an empty lines:
$ sed '/^$/d' example.txt
Remove a last line:
$ sed '$d' example.txt
Remove a first line:
$ sed 1d example.txt
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