Why is my database using Partitioning? ( I know it's not )
According to this documentation, this will return a value if the database has any of the following:


Partitioned tables
Partitioned indexes
Partition schemes
Partition functions


So check for and remove any partition schemes or functions, even if they aren't in use. You can do this in the SSMS UI (Database > Storage > Partition Schemes/Functions), or by querying the following system views:


sys.partition_schemes
sys.partition_functions