Hi Sarita
1) Dismantling an equipment can be done by using transaction IE02.
2) Some master data can be easily deleted and some need archiving. If you are asking for Functional Locations and Equipment records, you need to run archiving. (Transaction SARA). As archiving is not something you do regularly, we usually recommend creation of a specific Functional Location for the obsolete equipment and functional locations. Make sure the Equipment or Functional Location is inactive, and deletion flag is set for it. And install it under this specific functional location.
Regards
Savas