Unfortunately at the present time, the app hasn't implemented a management of hashtags so they cannot be edited or deleted. However you can try the below workaround solution to remove the undesired hashtag from your transactions and re-tag them with a new hashtag.
1. Create a filter for the hashtag you would like to edit or delete.
2. Once the filter is created go to Records and click on the filter icon on the top right corner of the screen (the three dots).
3. A pop up screen will appear. Click on the dropdown arrow to select the filter you created for the hashtag and click OK.
4. All transactions that have been tagged with the hashtag will appear. Long press one of the records and select the other records to edit multiple records at once.
5. Click on the pen icon at the top to edit the selected records.
6. Under the description section click on the box and type your new desired hashtag.
7. Click Ok to Save.
Now your records will be tagged with the new hashtag you entered. Unfortunately, the undesired hashtags will still exist and appear inside the app. However no records will use it unless you use the hashtag again.