workflow disassociation

I have a CustomList and a custom VS - WF is associated. On each item created in the customList - a WF Task is created by the WF this WF task list is a custom TaskList with a custom Content Type.

whenever I remove the association of th开发者_StackOverflowe WF from the customList - all the TASK in the Task list gets deleted.

is it the default behaviour ? Is there any way to retain those TASKs instead of it getting deleted ?

Yes, this is the default. Preventing workflow tasks from being deleted, when the workflow which created them is deleted is not possible out of the box.

The only way you have is to create an event handler for the task list which waits for ItemDeleted and then cancel the deletion. This is explained in the following blog post: Prevent Workflow Tasks From Being Deleted