Protractor:How to remove extra space from string just like we use in java getText.trim()

Andreas' solution is basically correct. I'm just appending some additional info.

I'm not sure what you're using the trim for, but

1) if you're trying to put it into an assertion:

expect(rows.get(9).getText()).toMatch('\s*STRING_TO_MATCH\s*')

or simply

expect(rows.get(9).getText()).toContain('STRING_TO_MATCH')

2) If you want a promise that returns the trimmed value

var columnvalue=rows.get(9).getText();
var columnvalue1=columnvalue.then(function(text) {return text.trim();})

The getText() method returns a Promise object. You need to do like this to get the string:

rows.get(9).getText().then(function(text) {
  console.log(text.trim());
});

If you look at the error you got you will see that it's trying to access the method trim() of an object, not a string.