cat /etc/pki/ca-trust/source/README

=============================================================================
QUICK HELP: To add a certificate in the simple PEM or DER file formats to the
            list of CAs trusted on the system:

            Copy it to the
                    /etc/pki/ca-trust/source/anchors/
            subdirectory, and run the
                    update-ca-trust
            command.

            If your certificate is in the extended BEGIN TRUSTED file format,
            then place it into the main source/ directory instead.
=============================================================================


Trust a certificate

cp /path/to/certificate /etc/pki/ca-trust/source/.
update-ca-trust


Test

openssl s_client -verify 5 -connect  <serverurl>:<port>

or

gnutls-cli -p <port> <serverurl>

or

curl --head https://<serverurl>:<port>



Remove trust

rm /etc/pki/ca-trust/source/myCertificate
update-ca-trust