You need to follow the process which should be detailed within your own constitution or trust deed.
If you do not have the power to close your organisation down you will need to follow the process to make a change to your constitution; this should be detailed within your own constitution.
If there is no power to wind up or to change your constitution you may need to apply to OSCR for re-organisation (if you are a registered charity).
In a Trust this will usually be done by a majority vote of the Trustees.
In a voluntary association it will usually need formal approval and vote from the members of the organisation before it can go ahead.