diff --git a/dlls/msctf/categorymgr.c b/dlls/msctf/categorymgr.c
index 648352af85a..3f47140ead1 100644
--- a/dlls/msctf/categorymgr.c
+++ b/dlls/msctf/categorymgr.c
@@ -144,9 +144,37 @@ static HRESULT WINAPI CategoryMgr_RegisterCategory ( ITfCategoryMgr *iface,
 static HRESULT WINAPI CategoryMgr_UnregisterCategory ( ITfCategoryMgr *iface,
         REFCLSID rclsid, REFGUID rcatid, REFGUID rguid)
 {
+    WCHAR fullkey[110];
+    WCHAR buf[39];
+    WCHAR buf2[39];
+    HKEY tipkey;
     CategoryMgr *This = (CategoryMgr*)iface;
-    FIXME("STUB:(%p)\n",This);
-    return E_NOTIMPL;
+
+    static const WCHAR ctg[] = {'C','a','t','e','g','o','r','y',0};
+    static const WCHAR itm[] = {'I','t','e','m',0};
+    static const WCHAR fmt[] = {'%','s','\\','%','s',0};
+    static const WCHAR fmt2[] = {'%','s','\\','%','s','\\','%','s','\\','%','s',0};
+
+    TRACE("(%p) %s %s %s\n",This,debugstr_guid(rclsid), debugstr_guid(rcatid), debugstr_guid(rguid));
+
+    StringFromGUID2(rclsid, buf, 39);
+    sprintfW(fullkey,fmt,szwSystemTIPKey,buf);
+
+    if (RegOpenKeyExW(HKEY_LOCAL_MACHINE,fullkey, 0, KEY_READ | KEY_WRITE,
+                &tipkey ) != ERROR_SUCCESS)
+        return E_FAIL;
+
+    StringFromGUID2(rcatid, buf, 39);
+    StringFromGUID2(rguid, buf2, 39);
+    sprintfW(fullkey,fmt2,ctg,ctg,buf,buf2);
+
+    sprintfW(fullkey,fmt2,ctg,itm,buf2,buf);
+    RegDeleteTreeW(tipkey, fullkey);
+    sprintfW(fullkey,fmt2,ctg,itm,buf2,buf);
+    RegDeleteTreeW(tipkey, fullkey);
+
+    RegCloseKey(tipkey);
+    return S_OK;
 }
 
 static HRESULT WINAPI CategoryMgr_EnumCategoriesInItem ( ITfCategoryMgr *iface,
diff --git a/dlls/msctf/tests/inputprocessor.c b/dlls/msctf/tests/inputprocessor.c
index 8173562cf06..be53391fbf1 100644
--- a/dlls/msctf/tests/inputprocessor.c
+++ b/dlls/msctf/tests/inputprocessor.c
@@ -177,9 +177,9 @@ static void test_UnregisterCategory(void)
 {
     HRESULT hr;
     hr = ITfCategoryMgr_UnregisterCategory(g_cm, &CLSID_FakeService, &GUID_TFCAT_TIP_KEYBOARD, &CLSID_FakeService);
-    todo_wine ok(SUCCEEDED(hr),"ITfCategoryMgr_UnregisterCategory failed\n");
+    ok(SUCCEEDED(hr),"ITfCategoryMgr_UnregisterCategory failed\n");
     hr = ITfCategoryMgr_UnregisterCategory(g_cm, &CLSID_FakeService, &GUID_TFCAT_DISPLAYATTRIBUTEPROVIDER, &CLSID_FakeService);
-    todo_wine ok(SUCCEEDED(hr),"ITfCategoryMgr_UnregisterCategory failed\n");
+    ok(SUCCEEDED(hr),"ITfCategoryMgr_UnregisterCategory failed\n");
 }
 
 static void test_FindClosestCategory(void)