Many leave the plant in the pots as it is unneccessary to remove it. However, I have found that the removal of the growing media(foam) is neccessary after a period of time because the plant simply outgrows it. When replanting a potted plant, it will be neccessary, and is recommended, that some of the root ball be cut away to promote new root growth. This is true of aquatic as well as terrestrial plants. The plant will exhibit some stress in the form of losing leaves, usually the more mature ones, since its feeding of these leaves has been compromised. This is not a big deal and will actually benefit the plant in the long run. One big benefit in leaving the plant in the pot is that it is much easier to move the plant when you have the inclination to do so. But, as I said before, it may become nccessary to remove the plant from its pot eventually.
When removing the plant fronm its "growers pot" just use a little patience and a sharp knife, pair of scissors, or even finger nail clippers (don't laugh, it works) to carefully remove the plastic pot. Next, gently roll the floral foam between your fingers or in you hands and carefully remove the media from the plant's roots. The keyword is patience.