A few thoughts, beginning with: there's no such thing as "de-baptism".

Once you are baptized, you are baptized. It's not just a "church rule" that one can't cancel a baptism, it's divine law. I can no more cancel my baptism than I can cancel having been born in Missouri. Admittedly, folks who deny there is a God will also deny that 'divine law' makes impossible de-baptism, but that's a problem for apologetics, not canon law. Anyway, as cheesy as internet "de-baptism" certificates might be, at least they provide the inimitable Jeff Miller over at Curt Jester with fodder for humor: Says Miller, Julian the Apostate, when he wanted to renounce his baptism, had himself drenched in bull's blood. Such a stunt, quips Miller, is "just as ineffective as an internet certificate, but it at least shows commitment." LOL!Second, the "de-baptism" fad does occasion (or, re-occasion, as the case may be) some questions about whether, notwithstanding the indelible character of baptism, one might be able to renounce one's Catholicism, indeed, one's Christianity. There are good arguments for and against the possibility that one can cancel one's membership in the Catholic Church or even abrogate one's identity as Christian (without "voiding" one's baptism, which is impossible). I mention this only to caution against overly-hasty resort to pithy expressions like Semel Catholicus semper Catholicus or Semel Christianus semper Christianus when what might have been meant was only Semel baptizatus semper baptizatus and what exactly that means.Third, signing these "de-baptism" forms does not, of itself, suffice for a "formal act of defection" under canon law (for an excellent article on this complex area of the 1983 Code, see J. Huels, "Defection from the Catholic Church by a formal act and the Circular Letter of 13 March 2006", Studia Canonica 41 (2007) 515-549), but signing such a form is certainly at least a step toward, indeed, objectively speaking, a sinful step toward, such defection. Moreover, the proliferation of these documents (not just in Britain, but around the world) is going to force some closer attention to several related issues in canon law, e.g., in criminal and matrimonial law, to say nothing of its serving as an topic for evangelization and catechesis focus.Finally, recognizing that the folks using such forms need our prayers (even if they don't recognize it), we might encourage the hundreds of thousands of persons coming into the Church this Easter to pray especially for those who wish to leave her. The newly baptized, and the newly received, flush with great graces, would make powerful prayer allies in this matter!