The capacity required to make or revoke a transfer on death deed is the same as the capacity required to make a will.
W. Va. Code § 36-12-8
Capacity of transferor
Known as the Uniform Real Property Transfer on Death Act
The act spans §§ 36–36 (17 sections).
Official source: West Virginia Legislature. Reproduced from public-domain West Virginia statutes; confirm against the official source for the current text. Not legal advice.