abap/objmgr/nodeletemode is a SAP Parameter attribute which is used to control Object Manager: no-delete mode (INTERNAL USE ONLY!) information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Only for internal use by SAP Support / for error diagnosis
See SAP Parameter Documentation for full SAP documentation for this profile parameter.