Ticket types are defined in the "Ticket - Types" dictionary (table llx_c_ticket_type).
In Dolibarr 10.0.1, the following types are predefined:
Change / Improvement
Project (disabled by default)
You can add / remove or activate / deactivate by going to Home> Configuration> Dictionaries> Ticket - Types
If a type is disabled in the dictionary, its column title appears in gray in the kanban view and you will not be able to drop in this column (as is the case here for "Project").