Dear …
Recently, the board of directors of __(name of our organization)__ had a good discussion on the association with __(name of other organization)__ over the past several years. Together, we have been able to accomplish some incredible achievements and it has been a lot of fun!
When discussing the new fiscal year goals for __(name of our organization)__, the board of directors all agreed that it is time now to take a new direction. Subsequently, we made the decision that, in the new fiscal year effective __(date)__, the direction we will be taking will be independent of __(name of other organization)__, allowing __(name of your organization abbreviated)__ to be recognized as a separate entity in the community.
We are more than willing to continue sharing space with __(name of other organization)__, but effective __(date)__, __(name of our organization)__ will have independent goals to pursue and will have its own phone. Whether or not we continue to share a computer will be a decision for __(name of other organization)__ to make. Some of these details will have to be sorted out through further discussions between our two organizations. And we want you to know that we are willing to cooperate as much as possible can to make this transition seamless.
On behalf of the __(name of our organization)__ Board of Directors, I want to thank __(name of other organization)__ and especially __(name)__, for all __(his/her)__ contributions over the years. It has been a great ride together and we wish you every success with __(name of other organization)__. We ask that you please extend our sincerest thanks and best wishes to the entire __(name of other organizarion)__ group.
Sincerely,