Take your time to double-check you have all your files backed up safely on a separate drive before doing any drive reformatting.
LDM is not a format I know and had to websearch to find out more. It is proprietary and for Windows.
This item may aid understanding. partitioning - How to read proprietary Windows LDM partition (or convert to NTFS) on Ubuntu? - Ask Ubuntu
I would also suggest you have a look at this forum item: Before you install