Why can't I uninstall a module if I deleted a field type in a content type?
You can try this process
Log into database and -&gt;
Select * from field_config where type = &quot;field_collection&quot;

Delete the rows
Same with field config instance table like
SELECT * FROM field_config_instance where entity_type = &quot;field_collection&quot;;

Delete the rows
You can also check.

1.) first remove all the fields inside the Fields Collection.
2.) Then remove the field collection from the content type
3.) Run the Cron
4.) try to disable the module, if you cannot then Go ahead with first query statements above.

Get more details Here.