When doing a credit qualifying Streamline Refinance at least one Borrower from the existing mortgage must remain as a Borrower on the new mortgage. Credit qualifying Streamline Refinances must meet all requirements of Manual Underwriting (Handbook 4000.1 II.A.5), except for any requirements for Appraisals or Loan to Value (LTV) Calculations.
For additional information see Handbook 4000.1 II.A.8.d.vi(C)(6) available at https://www.hud.gov/program_offices/administration/hudclips/handbooks/hsgh