CTLR REMOVED ACTIVE FLT PLAN ON SMA Z BY MISTAKE.

Narrative

I WAS WORKING THE NON RADAR POS AT ZID; NE LOVE. THERE WAS SMA X ON APCH AT ZZV. SMA Y CALLED FROM ZZV; VFR; REQUESTING AN IFR CLRNC. SMA Y WAS ADVISED THAT THERE WAS AN ACFT ON APCH. SMA Y DEPARTED VFR BUT COULD NOT CONTINUE TO CLB VFR TO GET ABOVE THE PROTECTED AIRSPACE FOR THE ZZV APCH. (ACFT TYPES USED IN NARRATIVE DUE TO SIMILAR CALL SIGNS.) WHEN SMA X CALLED; HE DIDN'T SAY MISSED APCH OR CANCEL IFR EITHER. HE REQUESTED AN IFR CLRNC TO HLG TO PRACTICE APCHS; THEN LANDED AT 2G2. WHEN ASKED IF SMA X COULD HOLD AT ZZV (SO WE COULD GET SMA Y A CLRNC); HE STATED THAT HE WOULD CIRCLE THE FIELD AND MAINTAIN 3500 FT (THE IFR MISSED APCH ALT IS 3000 FT). WHEN I ATTEMPTED TO REMOVE THE INLAND FLT PLAN (FP) ON SMA X I MISTAKENLY REMOVED AN SMA Z AT 7000 ON W SIDE OF AREA. AT THAT TIME; HLG SECTOR CALLED BECAUSE THEY SAW SMA Y CODE APCHING THEM; CLBING AND THEY HAD TFC AT 8000. THEY CALLED RADAR CONTACT (WE DID NOT SEE A TARGET) AND APPROVED IFR CLBING TO 7000. WHEN I TRIED TO DEPART THE OUTBOUND FLT PLAN ON SMA X IT WOULD NOT START (BECAUSE CORRECT INBOUND STILL ACTIVE). THE RADAR CTLR LOOKED UP THE FLT PLAN BY CALL SIGN AND STARTED A TRACK ON THE NUMBER OF THE FLT PLAN THAT WAS DISPLAYED. AT THIS TIME; THE R CTLR AND I BELIEVED THERE WERE 2 COMPUTER NUMBERS ON THE INBOUND FOR THIS ACFT AND THAT HE HAD TAGGED THE SECOND. IN REALITY; THE INBOUND TRACK HAD JUST MOVED OVER. SINCE THE PLT REQUESTED PRACTICE APCHS; THE R CTLR SUGGESTED THAT I AMEND THE FLT PLAN TO LAND AT HLG AND ADD 'DEST 2G2' TO THE 'PRACTICE APCHS AT HLG' THAT WAS IN THE REMARKS SECTION. I DID THIS AND VERBALLY COORDINATED WITH HLG SECTOR TO MAKE SURE THEY UNDERSTOOD. IN RETROSPECT; I REMOVED THE WRONG FLT PLAN. NO EXCUSES. I DIDN'T REALIZE THE ERROR BECAUSE THE 'PRACTICE APCHS' AMENDMENT SERVED TO CHANGE THE INBOUND FLT PLAN TO REFLECT THE OUTBOUND DEST. IN MY MIND; I HAD REMOVED 1 FLT PLAN AND STARTED ONE AS NORMAL. THOUGH NOT CAUSATIVE; THE QUESTION OF SMA X THINKING HE WAS VFR AND SMA Y STUCK UNDER THE CLOUDS VFR REQUESTING IFR CAPTURED MY ATTN. THE ERROR WAS BROUGHT TO MY ATTN WHEN THE INVESTIGATION BEGAN LATER THAT DAY.