If a Design Library part is placed in a part file, then following procedure is used to break the link with design library according to YouTube video search.
If a Design Library part is placed in an assembly file then file is converted into part file, will the part, break the link with Design Library? Because in this case no procedure is used to break link with design library, according to YouTube search.
Please note that this utility is only used for Toolbox components and NOT components from Design Library. Toolbox and Design Library are both different things in the SOLIDWORKS context.
The purpose of this utility is to convert a Toolbox part to normal part or vice versa.