这个 INDEX33555693 可能是主键，你试着用下面这个SQL查一下，看能否找到索引对应的约束名以及约束类型，然后就可以 ALTER TABLE xxx DROP CONSTRAINT yyy 的方式来删除了。

WITH T_IDX AS
(
SELECT USR.NAME  AS USER_NAME                              --表宿主用户名
      ,SCH.NAME  AS SCHEMA_NAME                            --表所在模式名
      ,TAB.NAME  AS TABLE_NAME                             --表名
      ,IDX.NAME  AS INDEX_NAME                             --索引名
      ,DECODE(IDXINFO.FLAG,1,'Y',9,'Y','N') AS GENERATED   --是否为系统自动生成的索引
      ,DECODE(IDXINFO.TYPE$,'BT','B 树','BM','位图','ST','空间','AR','数组') AS INDEX_TYPE     --索引类型
      ,RTRIM(  DECODE(IDXINFO.FLAG & 0x01,0x00,'正常索引;')
             ||DECODE(IDXINFO.FLAG & 0x01,0x01,'系统索引;')
             ||DECODE(IDXINFO.FLAG & 0x02,0x02,'虚索引(VIRTUAL);')
             ||DECODE(IDXINFO.FLAG & 0x04,0x04,'主键;')
             ||DECODE(IDXINFO.FLAG & 0x08,0x08,'在临时表上;')
             ||DECODE(IDXINFO.FLAG & 0x10,0x10,'无效索引;')
             ||DECODE(IDXINFO.FLAG & 0x20,0x20,'fast pool;')
             ||DECODE(IDXINFO.XTYPE & 0x01,0x00,CASE WHEN (TAB.INFO3 & 0x3F) IN (0x13, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27) THEN 'HUGE表聚集索引(HUGE CLUSTER);' ELSE '聚集索引(CLUSTER);' END)
             ||DECODE(IDXINFO.XTYPE & 0x01,0x01,'二级索引;')
             ||DECODE(IDXINFO.XTYPE & 0x02,0x02,'函数索引(FUNCTION-BASED NORMAL);')
             ||DECODE(IDXINFO.XTYPE & 0x04,0x04,'全局索引在水平分区子表上;')
             ||DECODE(IDXINFO.XTYPE & 0x08,0x08,'全局索引在水平分区主表上;')
             ||DECODE(IDXINFO.XTYPE & 0x10,0x10,'唯一索引;')
             ||DECODE(IDXINFO.XTYPE & 0x20,0x20,'扁平索引(FLAT);')
             ||DECODE(IDXINFO.XTYPE & 0x40,0x40,'数组索引;')
             ||DECODE(IDXINFO.XTYPE & 0x800,0x800,'该位图索引是由改造后创建;')
             ||DECODE(IDXINFO.XTYPE & 0x1000,0x1000,'位图索引(BITMAP);')
             ||DECODE(IDXINFO.XTYPE & 0x2000,0x2000,'位图连接索引(BITMAP);')
             ||DECODE(IDXINFO.XTYPE & 0x4000,0x4000,'位图连接索引虚索引(BITMAP);')
             ||DECODE(IDXINFO.XTYPE & 0x8000,0x8000,'空间索引;')
             ||DECODE(IDXINFO.XTYPE & 0x10000,0x00,'','索引不可见;')
          ,';') AS INDEX_EXTINFO                           --索引扩展属性
      ,DECODE(IDX.VALID,'Y','USABLE','UNUSABLE') AS INDEX_STATUS        --索引可用状态
      ,DECODE(IDXINFO.ISUNIQUE,'Y','UNIQUE','NONUNIQUE') AS UNIQUENESS  --是否唯一索引
      ,CONS.NAME AS CONSTRAINT_NAME                                                                    --索引关联约束名称
      ,DECODE(CONSINFO.TYPE$,'P','主键约束','U','唯一性约束','F','引用约束','C','检查约束') AS CONSTRAINT_TYPE       --索引关联约束类别
      ,CASE WHEN IDXINFO.KEYNUM = 0 AND IDXINFO.FLAG & 0x01 = 0x01 AND IDXINFO.XTYPE & 0x01 = 0x00 THEN 'ROWID' 
            ELSE DECODE(IDXINFO.XTYPE & 0x02,0x02,REPLACE(FBI_DEF(IDX.ID),'     ',' DESC')
                       ,(SELECT LISTAGG(COL.NAME || DECODE(SF_GET_INDEX_KEY_ORDER(IDXINFO.KEYNUM, IDXINFO.KEYINFO, COL.COLID),'D',' DESC'),',')
                                           WITHIN GROUP (ORDER BY SF_GET_INDEX_KEY_SEQ(IDXINFO.KEYNUM, IDXINFO.KEYINFO, COL.COLID))
                           FROM SYSCOLUMNS COL
                          WHERE COL.ID = TAB.ID
                            AND SF_COL_IS_IDX_KEY(IDXINFO.KEYNUM, IDXINFO.KEYINFO, COL.COLID) = 1
                        )
                       )
        END AS INDEX_COLS                                  --索引字段列表
      ,CASE WHEN CONSINFO.TYPE$ = 'F' THEN REFDEF(IDX.ID,1)
            WHEN CONS.ID IS NOT NULL THEN CONSDEF(IDX.ID,1)
            ELSE INDEXDEF(IDX.ID,1) 
        END AS INDEX_DDL                                   --索引创建用DDL语句
  FROM DUAL
  LEFT JOIN SYSOBJECTS TAB         ON TAB.TYPE$  = 'SCHOBJ'  AND TAB.SUBTYPE$ IN ('STAB','UTAB')
  LEFT JOIN SYSOBJECTS SCH         ON SCH.TYPE$  = 'SCH'     AND SCH.ID = TAB.SCHID
  LEFT JOIN SYSOBJECTS USR         ON USR.TYPE$  = 'UR'      AND USR.SUBTYPE$ = 'USER'  AND USR.ID = SCH.PID
  LEFT JOIN SYSOBJECTS IDX         ON IDX.TYPE$  = 'TABOBJ'  AND IDX.SUBTYPE$ = 'INDEX' AND IDX.PID = TAB.ID
  LEFT JOIN SYSINDEXES IDXINFO     ON IDX.ID = IDXINFO.ID
  LEFT JOIN SYSCONS CONSINFO       ON CONSINFO.INDEXID = IDXINFO.ID AND CONSINFO.TABLEID = IDX.PID
  LEFT JOIN SYSOBJECTS CONS        ON CONS.TYPE$ = 'TABOBJ'  AND CONS.SUBTYPE$ = 'CONS' AND CONS.ID = CONSINFO.ID
  LEFT JOIN SYSOBJECTS PAR         ON PAR.TYPE$  = 'TABOBJ'  AND PAR.SUBTYPE$ = 'INDEX' AND PAR.ID = IDX.INFO4
  LEFT JOIN V$TABLESPACE TS        ON TS.ID = IDXINFO.GROUPID
  LEFT JOIN V$HUGE_TABLESPACE HTS  ON HTS.ID = IDXINFO.GROUPID
)
SELECT *
  FROM T_IDX
 WHERE INDEX_NAME = 'INDEX33555693'