Although new roadmaps are able to be deleted, previously created roadmaps are not able to be deleted.
The banner error is:
rdm.cannotDeletePicklists
1. Obtain the roadmap ID from either the URL or HAR payload error
Example: http://[server]/pm/#/roadmap/5xxxxxxx/common
2. Create backup of the table create table: odf_picklist_contexts
3. Run the delete statement:
delete from odf_picklist_contexts
where object_code = 'rdm_roadmap_item'
and code = '5xxxxxxx::roadmaps::roadmapItems';
where 5xxxxxxx is the roadmap id affected.
Do this for each roadmap affected.