Go to "Forms" and choose your working ITR Form and click the "Manage Sections" (4 little squares).
Activate Spouse: Tick the Spouse section in the dropdown selection to be checked/activated.

Deactivate Spouse: Untick the Spouse section in the dropdown selection to be unchecked/deac.

Unlink Spouse from the Amended form
FAQ:
Q: Unlinking/removing spouse from the Amendment form.
A: First, unlink the Spouse from the Relationship section. How to "Activate" or "Deactivate" Spouse section?, Then amend the form and untick the "Spouse" from the Manage Section.
*How to unlink a relationship (e.g. Spouse) added in the Relationship section:
Go to the "Relationship" tab and then click the "Unlink" button to unlink the spouse (same process apply to remove or unlink any kind of relationship; like Beneficiary in Trust, Director.in a Company client account)
