Hello Michel,

Yes, you can remove this by doing change in language string.
Go to root/language/en-GB/en-GB.com_payplans.ini, near line no. 226, find below mentioned line of code

COM_PAYPLANS_DASHBOARD_SUBSCRIPTION_CONFIRM_FIRST_RECURRENCE_COUNT="%s for each %s, for %s installments"

Replace with

COM_PAYPLANS_DASHBOARD_SUBSCRIPTION_CONFIRM_FIRST_RECURRENCE_COUNT="%s for each %s"

Let me know if you have any query.