add file management feature (#560)

### What problem does this PR solve?

### Type of change

- [x] Documentation Update

api/db/services/document_service.py

@@ -15,6 +15,11 @@
 #
 from peewee import Expression
 
+from elasticsearch_dsl import Q
+from rag.utils import ELASTICSEARCH
+from rag.utils.minio_conn import MINIO
+from rag.nlp import search
+
 from api.db import FileType, TaskStatus
 from api.db.db_models import DB, Knowledgebase, Tenant
 from api.db.db_models import Document
@@ -69,6 +74,20 @@ class DocumentService(CommonService):
             raise RuntimeError("Database error (Knowledgebase)!")
         return cls.delete_by_id(doc.id)
 
+    @classmethod
+    @DB.connection_context()
+    def remove_document(cls, doc, tenant_id):
+        ELASTICSEARCH.deleteByQuery(
+            Q("match", doc_id=doc.id), idxnm=search.index_name(tenant_id))
+
+        cls.increment_chunk_num(
+            doc.id, doc.kb_id, doc.token_num * -1, doc.chunk_num * -1, 0)
+        if not cls.delete(doc):
+            raise RuntimeError("Database error (Document removal)!")
+
+        MINIO.rm(doc.kb_id, doc.location)
+        return cls.delete_by_id(doc.id)
+
     @classmethod
     @DB.connection_context()
     def get_newly_uploaded(cls, tm, mod=0, comm=1, items_per_page=64):