Try not to post in all caps next time. =)
As for disbanding fleets, it allows you to "disband" or remove ships that you have already built. Disbanding ships does not take up any turns...though you lose that ship for good (unless you build more). You decide the number of ships you want to disband...so you can disband one ship or your entire fleet.
The positives of disbanding ships is that you will probably have a higher income (ships not only cost money to build but there is a "interest" on each ship which takes up money for every turn you use). The negative side is that you will lose PR (amount depends on how many and what type of ships you disband).