Yes there is a product that you can buy in the likes of Atlantic etc,well worth getting,in fact its necessary,put it on the existing sealant,leave for the recommended time and the old ganky sealant just comes away easily.
Its very important that all and I do mean all the old sealant is removed before applying the new sealant otherwise it will fail in a very short time frame,not sure about tec 7 but my opinion is one sealant is as good as any other.
Applying sealant neatly is an art form,dab some fairy liquid on the end of your finger is a very handy (no pun) way of ensuring a professional/tidy finish.