An obsolete term is one that is no longer used, and has been "deleted" from the ontology. When a term (or relation or instance) is removed from active use, the term does not vanish; instead, it is marked obsolete. This ensures that the obsolete term's ID is tracked and not reused for a different term.
To make a term obsolete, simply delete all of its relationships to other terms in the ontology.
Once a term is obsolete, most of its attributes cannot be edited. Obsolete terms cannot have relationships to other terms, and most text attributes of obsolete terms cannot be modified.
However, it is possible to edit the definition and comments of an obsolete term. To edit an obsolete term, select it and follow the editing instructions described in the Text Editing section of this guide. Editing controls for uneditable attributes will be disabled.
OBO-Edit provides a mechanism to specify terms that can be used (e.g. in annotations or mappings) in place of obsolete terms. See Assigning Replacement Terms for more information.