You can't "remove the 0000000 from the date" - DateTime values don't work like that, they are stored as a number of ticks since a particular moment in time, so you can't dump the ticks!
But you can format the output:
string text = dt.ToString("s");
Will give you the UTC format:
2018-02-18T12:10:13
UTC does not have a timezone, so it wouldn't be "+05:30"
But this will add it:
string text = dt.ToString("yyyy-MM-ddTHH:mm:ssK");