Sometimes SEPM database grows big, if it is express DB it can lead even to SEPM malfunction if size will be close to 10 GB and reports similar message:
SEPM with express or remote database.
Logging settings configured cause the database to grow in large size.
Check the usage of that database via SQL Server Management Studio report:
This will show the specific usage by corresponding tables.
Most of the time it is logging that is taking to much space. Then those settings on SEPM have to be adjusted to decrease the log size.
Change is not instant it will take few hours sometimes even a day to start decreasing DB size.
Please also note that SEPM is not device that should store the logs history.
External logging should be configured for this purpose to keep SEPM DB in functional size.