The capacity required to make or revoke a transfer on death deed is the same as the capacity required to make a will.
Del. Code tit. 25, § 208
Capacity of transferor
Known as the Uniform Real Property Transfer on Death Act
The act spans §§ 25–25 (21 sections).
85 Del
Official source: Delaware Code Online. Reproduced from public-domain Delaware statutes; confirm against the official source for the current text. Not legal advice.