[DOCS] Add delete index alias API docs (#46080)

docs/reference/indices.asciidoc

@@ -35,6 +35,7 @@ index settings, aliases, mappings, and index templates.
 [[alias-management]]
 === Alias management:
 * <<indices-add-alias>>
+* <<indices-delete-alias>>
 * <<indices-get-alias>>
 * <<indices-alias-exists>>
 * <<indices-aliases>>
@@ -103,6 +104,8 @@ include::indices/types-exists.asciidoc[]
 
 include::indices/add-alias.asciidoc[]
 
+include::indices/delete-alias.asciidoc[]
+
 include::indices/get-alias.asciidoc[]
 
 include::indices/alias-exists.asciidoc[]

docs/reference/indices/delete-alias.asciidoc

@@ -0,0 +1,49 @@
+[[indices-delete-alias]]
+=== Delete index alias API
+++++
+<titleabbrev>Delete index alias</titleabbrev>
+++++
+
+Deletes an existing index alias.
+
+include::alias-exists.asciidoc[tag=index-alias-def]
+
+[source,js]
+----
+DELETE /twitter/_alias/alias1
+----
+// CONSOLE
+// TEST[setup:twitter]
+// TEST[s/^/PUT twitter\/_alias\/alias1\n/]
+
+[[delete-alias-api-request]]
+==== {api-request-title}
+
+`DELETE /<index>/_alias/<alias>`
+
+`DELETE /<index>/_aliases/<alias>`
+
+
+[[delete-alias-api-path-params]]
+==== {api-path-parms-title}
+
+`<index>`::
+(Required, string)
+Comma-separated list or wildcard expression of index names
+used to limit the request.
++
+To include all indices in the cluster,
+use a value of `_all` or `*`.
+
+`<alias>`::
+(Required, string)
+include::{docdir}/rest-api/common-parms.asciidoc[tag=index-alias]
++
+To delete all aliases,
+use a value of `_all` or `*`.
+
+
+[[delete-alias-api-query-params]]
+==== {api-query-parms-title}
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=timeoutparms]