DDL queries like CREATE TABLE don't work in Web Console.
First, if Ignite cluster is started with zero caches deployed then "Execute" button will be disabled and there is now way to execute CREATE TABLE in general.
Second, if to create a dummy cache on cluster startup and execute this
CREATE TABLE City ( id LONG PRIMARY KEY, name VARCHAR) WITH "template=replicated";
Then the console will generate the exception
Error: class org.apache.ignite.internal.processors.query.IgniteSQLException: CREATE TABLE can only be executed on PUBLIC schema.