add deletion of doctype

docs/easycozy/tips.md

@@ -7,7 +7,7 @@ All posibility are described in the [data section of Cozy documentation](https:/
 
 **Example**
 
-The example will describ how to query userChallenge data from an instance.
+The example will describ how to query userChallenge data from "ecolyotest" instance.
 First, you need to be able to connect to the instance in order to retrive the bearer and the cozysessid.
 
 ![Bearer&cozysessid](/img/bearer_cozysessid.png)
@@ -35,4 +35,30 @@ The result will then be retrieve by postman:
         ...
     ]
 }
-```
\ No newline at end of file
+```
+
+
+## Delete a doctype from a instance
+
+You can use ACH to delete a doctype. 
+Please find the [ACH documentation](https://npm.io/package/cozy-ach) to see all commands
+
+**Example**
+
+The example will describ how to drop userChallenge doctype from "ecolyotest" instance.
+the token provided is the one present in the cozysessid.
+
+```
+$ ach -t xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx -u https://ecolyotest.cozy.self-data.alpha.grandlyon.com drop com.grandlyon.ecolyo.userchallenge
+This doctypes will be removed.
+
+* com.grandlyon.ecolyo.userchallenge
+
+Type "yes" if ok.
+yes
+```
+
+A browser window will be opened asking for authorization to access to your file. 
+Just click on "Authorize" to keep on with the doctype droping.
+
+