Add ACH in SuiteCommerce MyAccount

Enable the Payment Instruments feature:
Go to Setup > Company > Setup Tasks > Enable Features (Administrator).
Click the Transactions subtab.
Check the Payment Instrument box.
Click Save.

Considerations Before Enabling Payment Instruments

The Payment Instruments feature provides new records, which may disrupt integrations with third-party commerce solutions. Previously, importing credit cards was sensitive with regards to PCI compliance. If supported by your gateway vendor, the new design enables you to import tokens that represent credit cards. The tokens are stored with your gateway service. Using credit card tokens diminishes PCI data security concerns.

Warning: Importing credit card data after enabling the Payment Instruments feature disrupts your integration. You must map the imported credit card data to the new Payment Card record.

Once the Payment Instruments is enabled on the account, by default, the permission level of the PI(Payment Instruments) is automatically set to full on standard customer center role. However, this is not the case if user is using a customize version of customer center role.
Navigate to Setup > User/Roles > Manage Roles
Note: Log in as an Administrator role
Click Edit link next to the affected Role/s
Go to Permissions > Lists subtab
Add the Payment Instruments and set the appropriate level
Level: Set Full

Automated Clearing House	Edit
Card holder authentication	Edit
Payment Card	Edit
Payment Card Token	Edit
Payment Instruments	Full
General Token	Edit

Click Add
Click Save.

create a payment method:

Go to Setup > Accounting > Setup Tasks > Accounting Lists > New , then select the Payment Method Type from the drop-down list in the Filters section, and then click New.
Enter a name ACH for the payment method in the Name field.
Select the Type of the Payment Method ACH from the drop-down list:
ACH – an online payment method that requires the Payment Instruments feature to be enabled. The method requires a token that was issued by a payment gateway and does not represent a bank account. The ACH payment instrument only works with the ACH payment method. The methodtype field value ID is 13.
Check the Display in Web Site box to use this payment method on your web store.
On the Account subtab, On the Payment Visuals subtab, choose which images show for this payment method on the web store checkout page as follows:
In the Flags column, enter the flag used to reference this image on your site.
If you are using a SiteBuilder website, enter web/standard. If you are using a SuiteCommerce Advanced site, you can use any flag used in the code on your site.
Note
If you enter more than one image with the same flag, each one of those images shows on websites that use this payment method.
In the URL column, paste the URL for the image you want to use for this payment method.
Warning: If you do not enter an image for at least one of your web store payment methods, the following error message shows on the payment information page: Payment Method: Unable to Proceed. This business does not have any external payment methods defined.
Click save.