Multitenant add-on: error in updating database

I am trying the multitenant add-on. After I have added the add-on to my existing project and run update DB scripts, I am getting the following error:

    No init scripts from 50-SDBMT have been executed, running init scripts
`Executing SQL script: /Users/mak/Projects/myApp/modules/core/build/db/50-SDBMT/init/postgres/10.create-db.sql
Nov 06, 2018 1:06:23 AM groovy.sql.Sql execute
WARNING: Failed to execute: 
alter table SEC_USER add column DTYPE varchar(100) because: ERROR: column "dtype" of relation "sec_user" already exists
:myApp-core:updateDb FAILED
FAILURE: Build failed with an exception.`
* What went wrong:
Execution failed for task ':myApp-core:updateDb'.
> Exception when executing SQL: 
 alter table SEC_USER add column DTYPE varchar(100) 

Aparently iyt seems that I already have run and created the entity but this happens even in first try before executing I see no such tables exist.

Anyways, we know we can inactive the sql script not to run again in this case but i do not see it. here is my directory appears:

the directory 18 doesn’t contain either. When I search in my computer, i see it is under WEB-INF. first question is, what is the reason of such exception and secondly how can i fix it.