First of all, we distinguish representation (the capacity to act on behalf of a third party, art.5 Law 39/2015) from registration in the REA (a means of accrediting the representation, art.6 Law 39/2015).
Any power of attorney registered in Representa is canceled through resignation, revocation or expiration, since it refers to the registration regardless of whether the registration was with or without validation (in the NTI project the reason field, in the case of resignations and revocations is optional).
In other words, canceling a registration in Representa does not necessarily affect the ability to act on behalf of a third party if, for example, valid powers of attorney are attached or a representative certificate is used when carrying out the procedure.
In the event that a representative makes a request, by virtue of a previously registered revoked representation based on the validation of legal documentation, and does not accredit this representation (or not sufficiently) the AAPP should require the amendment, not reject the procedure (art.5, section 3 in relation to app.6).
Therefore, to apply for deregistration at the REA, in this case at Representa, no special procedure or validating the deregistration is necessary, the will of one of the parties to deregister is sufficient an inscription
Without prejudice to the fact that it is not legally foreseen, the purpose of the validation is to check the capacity to act on behalf of another (that it really is a type A power of attorney, if there is any limitation due to the amount, etc.) ; in the case of cancellations, either by resignation or revocation, what prevails is the will of the person making the request.