Well, one way to do this would be to exclude the entire pool from assignment. This would leave the configuration of the pool in there and you would just remove the exclusion if you wanted it to assign addresses again.
ip dhcp excluded-address <first address> <last address>
However, I would just archive a copy of the config and remove the pool.
Configuring a DHCP relay on Cisco routers is pretty simple. You use the ip helper-address <DHCP server address> command on the layer-3 interface. The address for the helper address must be reachable from the router on which the helper address is configured, e.g. the Router0 interface toward Router1.
You are putting the helper address on the physical interface for which there are no VLANs. You need to put the helper address on the individual subinterfaces (each subinterface could use a different DHCP server).
Your DHCP server must have a scope for each of the networks for which it is the DHCP server.
By the way, never use a picture for text in your question. Just copy the text and paste it into your question, highlight the text, and use the Pre-formatted Text button: {}.
Edit:
Your Router0 needs scopes for VLANs 15 and 20:
ip dhcp pool vlan15
network 195.165.85.96 255.255.255.224
default-router 195.165.85.126
ip dhcp pool vlan20
network 195.165.85.128 255.255.255.224
default-router 195.165.85.158
Router1 needs helper addresses on the interfaces:
interface GigabitEthernet0/1.15
encapsulation dot1Q 15
ip address 195.165.85.126 255.255.255.224
ip helper-address 195.165.85.29
interface GigabitEthernet0/1.20
encapsulation dot1Q 20
ip address 195.165.85.158 255.255.255.224
ip helper-address 195.165.85.29
You also need to make sure that Router0 can ping the G0/1.15 and G0/1.20 interfaces in Router1.
Best Answer
As per your Description You are using SG350 switch as your core switch. Therefore it is not a good idea to Configure DHCP pool in this switch because it make additional overhead on your switch. In addition to that SG350 switch has limited feature for redundancy and therefore if there is a failure you will lost everything.
You can use separate DHCP pool such as ubuntu, windows or separate router such as netgear....etc. But i don't recommend to use DHCP pools on separate locations. You can move to all DHCP pools to separate DHCP pools. Otherwise It will generate additional complexity on your network.