Hello!
There are some are some tricky rules about how this type of disability income is reported and thus includable in taxable income. For example, some portion of the payments may not be taxable if you personally paid for the insurance providing the payment. But getting back to your specific question, If you are owing taxes when you file your annual tax return, you probably want to adjust your withholding so that is not the case.
If you no longer have dependents, then you are presumably not receiving the potential credits that go along with supporting dependents and your filing status may have changed, too.
I recommend you use this calculator to estimate what you will be paying this year in your current situation, meaning without dependents or with any other changes. https://turbotax.intuit.com/tax-tools/calculators/w4/
Then if you find you want to have amounts withheld, or change the amount withheld, from your LTD, you can submit this form to your insurance company. https://www.irs.gov/pub/irs-pdf/fw4s.pdf
