If your turnover has fallen below the VAT thresholds and you want to de register from collecting VAT then simply complete the attached and submit to your local Revenue Office.

http://www.google.ie/url?sa=t&source=web&cd=1&ved=0CBQQFjAA&url=http%3A%2F%2Fwww.revenue.ie%2Fen%2Ftax%2Fit%2Fforms%2Ftrcn1.pdf&rct=j&q=trcn1&ei=x-dzTMr4IcK4jAej-qiKCQ&usg=AFQjCNHAKAH0crU_JkdJmbQ1EiBih89u0w&cad=rja