def delete_feature_classes_and_tables(workspace=None, schema=None):
    if workspace:
        old_workspace = arcpy.env.workspace
        arcpy.env.workspace = workspace

    if schema:
        feature_classes = arcpy.ListFeatureClasses('*.{0}.*'.format(schema))
        tables = arcpy.ListTables('*.{0}.*'.format(schema))
    else:
        feature_classes = arcpy.ListFeatureClasses()
        tables = arcpy.ListTables()

    if feature_classes:
        for feature_class in feature_classes:
            arcpy.Delete_management(feature_class)

    if tables:
        for table in tables:
            arcpy.Delete_management(table)

    if workspace:
        arcpy.env.workspace = old_workspace

delete_feature_classes_and_tables(r'D:\Users\username\Connection to localhost.sde', 'dbo')