LUI-135 Deleting complex obs should not lead to loss of data.

Have you read the openmrs users guide? If yes, can you now try reproduce the reported problem in your running instance of OpenMRS? https://wiki.openmrs.org/display/docs/User+Guide

So I went through the link, I seem not to find how to solve some of the issues over this link especially concerning running the instance

Of course we cannot be of help concerning any issues or problems you face but are not describing in detail.