DBCC SHRINKFILE('DB filename', 10240)
OR for MDF file
DBCC SHRINKFILE(1, 10240)
But if you have more than 10240 Mb of data in MDF file - it woun't help, then you have to add extra file to DB - where to move extra data from MDF file.
Shrinks the size of the specified data or log file for the current database or empties a file by moving the data from the specified file
to other files in the same filegroup, allowing the file to be removed
from the database. You can shrink a file to a size that is less than
the size specified when it was created. This resets the minimum file
size to the new value.
How to know filenames in DB:
SELECT file_Id, name FROM sys.database_files
Shrinking data files always affects performance - it makes it worse, so you really need to have a REASON to do that.