Here we are going to do a conversion of standby database. First of all, we convert the standby to a snpshot standby.
Go to database home page, click standby database.

Data Guard in Cloud Control 12c
Go to data guard administration page.

Data Guard in Cloud Control 12c
Click [Convert] to convert to a snapshot database.

Data Guard in Cloud Control 12c
Select correct credential name of standby server, then click [Continue].

Data Guard in Cloud Control 12c
Confirm to convert.

Data Guard in Cloud Control 12c
Converting is processing.

Data Guard in Cloud Control 12c
Converting is completed.

Data Guard in Cloud Control 12c
The page returns data guard administration.

Data Guard in Cloud Control 12c
Refresh the page to make all status current. Then click [Convert] to convert back to physical standby.

Data Guard in Cloud Control 12c
Select correct credential name of standby server, then click [Continue].

Data Guard in Cloud Control 12c
Confirm to convert back to a physical standby.

Data Guard in Cloud Control 12c
Converting is processing 1.

Data Guard in Cloud Control 12c
Converting is processing 2.

Data Guard in Cloud Control 12c
Conversion is completed.

Data Guard in Cloud Control 12c
Refresh the page and all status are back to normal.

Data Guard in Cloud Control 12c